I'm borderline on the matter. His models do genuinely look bad, and it doesn't seem like he wants to improve; But I don't think drama is going to do him any favors either.
QFT.
You don't have to force him to change. Like seriously, its his prerogative to make bad models. You don't have to go out of your way to insult his methods. If he thinks he's the hottest stuff in modelling, you probably cannot change that either.
I just don't think that saying
All of your models are complete stuff Pi. I'm not a professional modeler or anything, but even I can tell a stuffty model from a decent one.
a hundred times will do anything for anyone.