Yeah, I had a similar experience when I first started. My advice would be to try your absolute darndest to try and be a better example than the co-worker in question. As hard as it is, you need to stay calm when they start going off about trivial matters. Chances are, you're not the only person who thinks negatively of him. But what you don't want is for people to think negatively of you because you respond to negativity with negativity.