As someone who works in a design field, I can tell you (at least from my perspective) that it doesn't feel like an insult, but it's certainly not always helpful to constantly critique something to no end. Everyone likes to think their input is helpful and for the better, but it just doesn't always work out that way.
It more or less just feels like the the client will never be happy, much like many ppl on this forum actually
I'm not saying to accept mediocrity, but everyone has to accept that there are some limitations be it by the company and/or the factory as well as interpretation differences like what the correct color is of something or what the proper build of a character is, etc. It's going to pretty much vary person to person. Like those pics where some ppl saw a blue dress or some other color or whatever that social media trend thing was.
EDIT: Lastly, there comes a time where you just have to stop revising and just release the product, otherwise it may never come out. Guaranteed, there will ALWAYS be someone that will say "if you could just change this or that one thing, it will be PERFECT!" but, no matter how much you cater to them, there will always be something else that could be done. TDK Joker is a perfect example of this. It could be a scan of Ledger himself and there will still be someone who says "no, it's off. So and so did it better. If they could just do ____ then it will be the perfect likeness"