Ask HN: What makes you not want to work with a developer?

A big one for me is otherwise smart people who immediately start bashing/complaining about a language/framework that they just learned or aren't familiar with. A lot of times they make mistakes due to not knowing it well and end up putting the blame on the language/framework.

I once worked for a small startup doing React development. One day we hired a new developer who came from an Angular shop. Literally on day one he was questioning why we weren't using Angular and suggesting that it might be easier to just rewrite from scratch. This guy complained for the next couple weeks and was super bitter towards using React despite the fact that most of his problems were caused by not understanding React well enough.

I guess it boils down to: just because you're used to something doesn't mean its better.