I just say or do what's on my mind. So, uh, I kinda can't accurately portray how I'd deal with criticism without knowing first whatever is being criticized.
Good example: the very first negative review I received was well founded. It was on one of my early stories about a character that had gone mute and no one could gather what she was wanting. Well, the review I received stated that pencil and paper exist, thusly, everyone has been hit with retardation.
...Yep, I totally agree with that. I devoted an entire following chapter to that reviewer on how stupid everyone was last chapter. I even had one of the cast give the mute character an old toy called the Etch A Sketch.
Now as for another example: I had flipped my top on another reviewer who harassed a number of other writers for including heterosexual relationships. This person didn't just bash the novels, but had also called the writers trash, or in one memorable comment, a "hack." It's not possible to know their name because they kept making up new ones. That was until they commented on one of my novels... I think once I went public about their behavior, the rest of our community decided they had enough too, and the toxic relationship we had with this person had at last folded to a close.
But, yeah, I say what pops in my head, and sometimes that isn't very smart. Burning bridges is not a constructive practice, so I try not to be mean.
Just to note: these events occurred on TGStorytime. You can still find these two interactions there in my review section, and the big blow up in an archive belonging to the TGStorytime Reviewer's Club.