I think what people honestly want to know if you see the mistake - if it jumps out at you. Sometimes it does, and sometimes it doesn't. There was a post in the last few days where the quilter put two squares of the same color next to each other. I never did figure out where those two squares were. I didn't look really hard, but it did not jump out at me. Had I posted an opinion, I would have said leave it.
On my first quilt (D9P), I had a mistake. One of the squares was too small (not consistent enough seams), so I had to move it to the bottom corner where it wouldn't make every other square not match up. That put it next to a square that was the same color. I asked for other's opinions. (The question really was, "Is this noticeable enough that it's worth remaking the square, cutting it up, Mr. Seamripper, etc." and, "Will I always see this mistake when I look at this quilt?" ) Most everyone said it was not noticeable. I didn't fix it and am happy with the way it turned out. I had to look for that mistake after a few months. At the time, though, all I could see was those two yellow squares in close proximity.
Other people's perspective helps sometime. I assume they tell me the truth as they know it.
bkay