Too often form Nazis berate lifters ballsy enough to post videos of their working sets on the internet for some arbitrary thing. Let's make sure we are clear on a few things before I go any further.
Good technique is established based on what is optimal to achieve a desired result and NOTHING MORE.
If heavy cheat curls are found to be extremely effective for adding girth to an aspiring bodybuilders arms and it isn't accompanied by any unforseen negatives, then it is good form.
If hitching a deadlift expedites the lockout, secures more reps in contest, and saves the glutes for later events in a strongman meet, then it is fantastic form.
And if a competitive Crossfitter..... who's sole reason for living is to do well in a CROSSFIT COMPETITION, not meet the military's standard for a good pullup... finds that kipping like a madman is the difference between last place and the podium, THEN IT'S THE BEST FORM ANYBODY COULD HAVE EVER CONCIEVED OF.
Understand that there is a difference between training for strength and demonstrating strength. In some parallel universe where bent rows are contested as a strength exercise, I'm sure there would be some strict standards that we would all need to follow so that achievements can be compared on some sort of level playing field. But in this universe they are simply a means of getting a big, strong upper back and using a lot of intensity, a limited range of motion, and plenty of swaying and swearing is the best way to meet that end.
The things we compete in are arbitrary. At some point in their life, a person looked at an athlete in a certain sport and said, "I want to do that". Bench pressing does not contain more moral virtue than a clean and jerk, and neither of those pleases Jesus any more than triathlons or ping pong. You can choose to have a meaningful discussion on the different adaptations that you will make as a result of training for these sports (strength vs endurance vs coordination etc), but the value attached to those are personal and subjective and do not diminish the accomplishments of other world class athletes simply because they are different.
Kipping pullups are not, and have never been, the recommended way to getting a big strong back. But neither is riding a bike or swinging a tennis racquet. If you decide to compete in an arena that allows (and thusly requires) a specific technique that may benefit you, it is your duty as a competitor to be the absolute best there is at it.
Now that we have that out of the way...
Faulty technique in competition setup will cause one or more of the following:
Movement into a weaker position (as a result of mechanics or weak muscles)
Loss of rigidness or stability that contributes to efficient force transfer
The imminent possibility of injury
Making sure these problems are taken care of is priority number one. Any setup that eliminates anything on this list will guarantee a successful foundation to build off of.
Notice that this list doesn't include training tactics for building muscle mass or improving capacity. Movement into weaker positions is actually ideal when attempting to build or strengthen a specific area. Deficit deads, close grip bench presses, and front squats worsen levereges so a specific muscle/group has to endure more strain and, thus, grow. This is another example of how training for strength is different than demonstrating it.
Now let's talk about most of the irrelevent garbage that people fixate on.
A misguided (and arbitrary) sense of 'strictness'
Novice bodybuilders are notorious for nitpicking swinging on curls, delt raises, and more. And don't make me go back to the kipping pull-up discussion. Strict is good for isolated development, kip is good for increased cardiac output. And for such a sacred goddamn cow in mainstream strength culture, I don't know a lot of people with really jacked lats that put a pull-up over a row or pull-down for development. Gymnasts and Crossfitters use it for the same reason: it's the most efficient way to get your ass up to a bar. Moving on.
The appropriate amount of strictness is going to be based on one of two things: what is optimal for development in TRAINING and what meets standards set forth in CONTEST. These are different. Judge for yourself if cheat curls with 225lbs is impressive or not. But if somebody does them to get really big arms.... and they have really big arms..... then get off of their back. So many different techniques are utilized in the acquisition of strength and size, from extreme range to partial range, super strict to super sloppy, that it is ridiculous to suggest one is better or worse for all lifters at all times.
This reminds me of an argument from years back when Derek Poundstone posted a video of him doing a set of deadlifts in training. Being a competitive strongman (and one of the best in the world at the time), he trained in contest conditions: suit, straps, hitch, bounce. The video was with 800lbs..... for 9 reps. Of course that one guy came in with 'I counted 1 rep and 8 bounces'. So here is one of the best deadlifters in the sport, and the only guy in the world at the time that routinely beat Zydrunas Zavickas in contest, having to explain his training methods to some troll in an internet forum. Training without a suit, a hitch, and a bounce is a disadvantage to someone who competes in the wild-west of strength sports where anything goes. He did what met his specific needs for training and contest and it worked. The proof is in the pudding.
Popularized setups/cues from your favorite lifter
This grinds my gears more than just about anything else. Long term, people get really good at what they train. Every time I see a coach trying to deconstruct the way an intermediate lifter has been training successfully for years to fit into some cookie cutter mold perpetuated by an idolized lifting guru, I want to walk into traffic. And lifters do it too, forcing their dumpy 5'9" frames to accommodate a technique used by their 6'6" lifting idol.
A super high arch with elbows tucked into the sides and the bar halfway down your belly is not a 'powerlifting' bench press in any other sense than that is the only thing it is useful for. This, like the chest-up-knees-out-hips-back cue for a sumo triple ply squat setup, is extremely specific and may work well for a lifter that has specific leverages and has spent a lot of time dialing it in. But it should by no means be THE way for teaching the lift. Successful lifters develop different habits for themselves over time based on individual need and these same lifters will consequently become very good at whatever method they incorporate. Watch Vogelpohl and Chad Smith squat. Eric Spoto and Brian Siders bench. Konstantinovs and....well... anybody else deadlift. Anybody who has one way of teaching a lift gives themselves away as not having a clue.
Fixing things that have no net change on the outcome
Arbitrary coaching is a cancer and is most often used when the coach wants to feel like 'coach' but doesn't have anything meaningful to say. The only reasons energy should be wasted breathing a technical cue to a lifter is if they are doing something that compromises the training effect through inefficient or unsafe positioning.
There are only going to be so many things that will have a meaningful change on the short and long term development of a lifter. Much of what a lifter does is going to be arbitrary and a simple matter of personal preference. Another internet war I foolishly waged in my youth was over an absolute statement someone made about elbow position in a squat: that they should always be down! (Anytime someone says 'always', politely excuse yourself from the argument. You've already won.)
Excuse me while I pull videos from 5 elite lifters in 5 seconds that clearly drive their elbows up.
Excuse me while someone says 'exceptions to the rule' and I blow my brains out.
This actually may have a change on the outcome: if you are having problems with bar slipping as a low bar squatter, elbows up could help secure the bar, and high bar squatters may find maintaining an upright position to be marginally easier with elbows down. But these are going to change on a case by case basis and will not make a damn bit of difference to anybody not having these specific issues. But sure enough, there is someone in some gym yelling 'elbows down!' to every single lifter of his that steps under a bar. Sure enough, a novice trainee is spending in hour in the mirror practicing a different elbow position when there isn't anything actually wrong with the bar position.
The next time you are reading an extensive article on the butt-wink, think if changing your setup or doing 18 hours of mobility work is really going to make you better at what you do. Technical changes should offer predictable, concrete improvement to your game, and if it doesn't, then scrap it. There's only so many hours in the day, so don't waste time obsessing over the small stuff.