That's the bottom line right there: thinking that recommendations are useful to YOU is naive and missing fundamental things about the experience.
That said, you can indeed tell them what you like but by use of negative space. When you get bombarded with obviously horrible recommendations, do the two-step process of clicking 'Not Interested' (if possible without even watching the video, or you can check it in incognito mode, assuming they're not watching that even more closely) and then 'tell us why', and respond 'I'm not interested in this channel: "undesirable video maker".
That assumes you can be sure you want to nuke the channels and subjects in question, but when it's clickbait channels and/or alt-right propaganda it's generally easy to identify and not get wrong. I'm sure the same would be true for leftwing propaganda, but the stuff I don't want pushed on me has a whole language and lexicon that's easily recognizable by video title, channel title and attempted clickbait image. If stuff trips my sensors on those grounds, I'm generally comfortable nuking it unseen.
That said, you can indeed tell them what you like but by use of negative space. When you get bombarded with obviously horrible recommendations, do the two-step process of clicking 'Not Interested' (if possible without even watching the video, or you can check it in incognito mode, assuming they're not watching that even more closely) and then 'tell us why', and respond 'I'm not interested in this channel: "undesirable video maker".
That assumes you can be sure you want to nuke the channels and subjects in question, but when it's clickbait channels and/or alt-right propaganda it's generally easy to identify and not get wrong. I'm sure the same would be true for leftwing propaganda, but the stuff I don't want pushed on me has a whole language and lexicon that's easily recognizable by video title, channel title and attempted clickbait image. If stuff trips my sensors on those grounds, I'm generally comfortable nuking it unseen.