Let me start by saying that I need to improve big time and I'm doing my best, so I always very happy to get critiques and criticism alike. I actually listen, because there's always something to learn, especially at my level. Still, I'm a busy person and I am confident enough to know that I can't and won't ever spend my time second guessing what I'm doing, especially from the writing point of view.
So, it's happened just recently. It was a requested critique, and let me also point out that this offered to go more into a more detailed discussion about his critique, if I wanted to. Now, he completely completely botched about a million things about my comic. I thanked him, and politely asked him to wait until the end of the part of my comic he had been reviewing, so we could get back to it. At that point, I highlighted some of his most obvious mistakes along with a couple of assumptions he made that were obvious guesswork (he didn't know the final events of that part), explained a bit more about the characters, and asked him to please tell me how he'd see the events evolve. This time, it was plain as day to me that he was more interested in giving his own spin to my story than getting what I was doing, so I just thanked him again and moved along. He meant well, but didn't really help much. Still, it was a requested critique (since he offered), and it was fine.
Should I get any unsolicited criticism resembling this guy's, I would very likely thank the person, politely express that I really meant to do something else (without spoilers), add a brief explanation of why (if I felt like it), and move on.