Don't let trolls bother you. Seriously. They're just noobs pretending to be cool.
But seriously, if you ever get a message from one and it actually does kind of offend you, don't respond to it and report it. Or just hide the comment, forget about it, and go on your merry way.
However, you can also respond humorously. Like so...
TROLL: I hate you and your art sucks.
ME: You be hatin' I be laffin'
TROLL: Zelda sucks.
ME: *hits you with Hylian shield and knocks you unconscious* ROFLFACEPUNCH
ME: YES! I've always wanted to be famous!
TROLL: Why are you so stupid?
ME: I have no idea. I think it's because my sheer awesomeness blocked out the smart part of my brain and overtook me altogether.
TROLL: No one likes you.
ME: O rly? Fascinating. Why don't you tell that to my 200 watchers? <---- (I don't actually have 200 watchers that was just an example
TROLL: You're mean.
ME: Did you know that if you scramble the letters in "mean" it spells "amen"? COOL, RIGHT?
I just figured that out!
Of course, you should never respond to a troll with a snarky, offensive comment of your own, because that opens the door for retaliation. Just report them, ignore them and don't let it ruin your day.