That explaination doesn't hold water. I see the same kind of grossout videos occasionally surface in search results. I
never engage with content anything like that. I don't use an account, but I do have a cookie set for personalized suggestions. This cookie is never more than a few months old. I don't share this device with anybody. I'm not getting recommendations from other people sharing my IP, all my video recommendations make sense for me
except for these gross out videos. There isn't another trace of other people's interests, for instance zero sports content despite sports being extremely popular with the general population. Finally, several other people have reported this same sort of behavior from youtube.
Aside, I find it really disheartening how quickly people on this site of all sites are to conclude "I don't see that, so you're holding it wrong". The most likely explaination is these results are some experimental feature run amok. You should know that companies like Google run all kinds of AB tests on the unwitting public, so one person not seeing something should never be taken as proof that another person is imagining it! This kind of "I'm not seeing it so you must be doing something wrong" comment is effectively gas-lighting when it comes from people who work in or near the industry and should know better.