To me, there is criticism that gives suggestions on how they think a story might be better, and criticism that simply points out what they think is bad.
Now how someone views the quality of each type of criticism depends upon how much of a thick skin they have, if they are looking for praise, just the opinions of others without regard to whether it’s positive or negative, and/or how detailed the critics are and how well constructed their arguments are.
If someone says, “I don’t like the MC, he’s too dumb and too beta,” while I bet to most it would be seen completely unhelpful and just over all insulting, while it is that in the sense of not giving much of what the poster actually thinks of the story, it is helpful in determining what type of characters the poster likes, which if plenty of other people are posting the same thing and you are writing your story for it to get popular, is legitimately helpful in tailoring your story to the audience.
Some of you may think that’s soulless, but for those types of people, it is helpful. If you want to write for just yourself, no need to listen to what I said above and just skim the criticisms for ideas to take for your story and don’t bother with feeling in any way obligated to listen to them, especially since in your case the story isn’t for others, it’s for yourself.
If you want to improve as a writer in accordance with the standards of others, or at least in accordance with your standards that in some way include the opinions of others, then just skim the criticisms that all say simple things, like the ones that just say, “I think X thing is bad,” though if plenty of people are saying the same thing, while that doesn’t mean they are correct, it means there is a high possibility that something they are finding wrong in your work is, if you re-examine your story, something that you also would find wrong.
For criticism that is highly detailed and isn’t just a repetitive way of saying the same thing over and over in slightly different ways, (trust me, I’ve seen that type if thing before all while the poster says they’re giving out good, highly detailed and constructive criticism,) make sure to read over it, look at its arguments and for weak and strong points in its logic, then see how you would like to apply what they’ve said to your story, and, if you can, respond back in a constructive way (good arguments and what you like and dislike about what they’ve said) for what you think you’ll use of their criticisms.
And a big point here for both the authors and the critics, you can insult their arguments and what they’ve written all you want, though it still isn’t a good idea for constructive conversation, but insulting the posters themselves is a good way to lead into a flame war.
This is the advice I have. Thank you for coming to my *cough* Ted Talk. :P