For the "your dps sucks" line, I got it once some time back during a lvling dgn. Was either Qarn or Brayflox, one of those two.
I remember stopping for a sec, trying to think and then finally said "Ok. How is it sucking?"
Person said "go figure it out scrub."
Then I said "ah so u don't know either"

Let's just say that did not end well. I find it funny that the person who was calling me out didn't know any better and was getting more heated until he left on his own. Thinking about it back then, I can't help but laugh cause I had played the game for a few months and was just getting to know how some jobs worked. In addition, I was convinced that lvling roulette was a good place to apply theory and I figured people would actually explain if I was screwing up something.

Guess some of them are just content to point out what someone else is doing bad only. If you are gonna do that, you need to follow up. Now if the person is still not receptive, that's out of your hands.