I know got one of two (always one or the other) execution clips (as in, a human kneeling in front of someone with a weapon, at least according to the thumb, never watched it) when scrolling to far totally benign searches (namely remixes of songs that have a lot, trying to find some I like). I did click "not interested", and after a few months it popped back again. up Couldn't find it right now, so maybe it got reported often enough, but my guess would be the "algorithm" "realized" that this video got a lot of clicks regardless of search, so why not sprinkle it into all searches, right?
And that's silly, and I claim it would be even with perfectly good intentions. It's just wasting huge amounts of energy on something that is worse, and cannot ever be good (that is, the whole algorithms second guessing people stuff). Give me "dumb" search that returns things that contain the terms in the title or description, or that are linked in the descriptions of videos that contain them. Or even find an open way (i.e. not restricted to Google, and not "the way Google likes it", but decent and simple and clean) to show videos on web pages that contain them. Page rank is not perfect and can be gamed, but it's actually feasible to make that good -- it used to be stellar compared to what we have now, now imagine what we could do with all that was learned and invented in the meantime.
Crafting searches to make pinpoint landings on what you are looking for, if it exists, is a delightful art. Remember http://www.fravia.net/ ? It's like remembering having and being able to use a screwdriver, instead of there being this fairy that you can ask for help, which sometimes shows up instantly and fastens the screw, and sometimes shows up pretending to not know what a screw is while reaching in your pocket... which is at best as good as having and being able to use a screw driver, and potentially infinitely worse. So on average, it's infinitely worse. Logic :D
And when it comes to clicking "not interested", I know that in the long run my wishes aren't respected anyway, and I've gotten so cynical about this stuff that I basically just view it as a further signal to a bad actor (if not abuser) that yes, I saw this thing, didn't just scroll by it, noticed it enough to strongly dislike it, and am now offering a futile plea to please not show me that again. I'd rather close the tab altogether.
This rant wasn't directed at you or your suggestion, not at all! But I just had to get it out, I hope you understand. I'm so over the whole web as a worse version of TV, where the middlemen get the vast majority of profits plus information on how to better poison you, and you get the poison.
Teach people digital literacy instead of giving them "free" assistants that very well might one day become their captors or worse, to the degree they aren't already.