In order to provide signalling, you have to watch a video, incognito, and then, after determining the video's instrinsic value, possibly re-watch it in cookied spyware (ahem! "normal") mode, so that the system is permitted to log "awareness" of your assent to recognize an alteration to your viewing habits.
Do you see how backwards that really is?
I wish there was an extension to remove all the "Recommended for you" entries and only show videos related to the current videos.
sadly this is not the case, you will still be flooded by "10 of X, you wont believe number 3" and "person Y stumped liberals with his totally not nazi speech" garbage
Youtube is just using ML algorithms so it's only going to be as good as the data you give it. Actively downvote and choose "Not Interested" for content you don't like and anything click-baity.
They are now organizing suggestions into topics so you can easily curate simply by hitting the X on topics that you don't like.
Of course, you need to clear your search and watch history too, otherwise all those clickbait videos you clicked on before will still be driving your suggestions.
"$7,000.00 Beta Starter Opened with OpenBoosters - BLACK LOTUS?" investment scam?
"MY $1MILLION DIAMOND INVESTMENT" mm Im seeing a pattern here
"Flat Earth: What Makes REAL Science? – Wisecrack Edition" wat?
Not to mention 10 out of 20 suggestions are videos I already watched and upvoted (I inject custom CSS into YT to make :visited visible again so I can skip it).
Getting shitty clickbaity/scam suggestions is not a given/reproducible, but they still happen often enough to be noticed on a daily basis.
So with that factor removed, my search/watch history actually seems to be driving cleverer selection of videos to recommend, not worse.
Here are my rules for YouTube:
1. Disable search and watch history. This restricts the factors that drive your video suggestions to videos you've explicitly selected.
2. Never go to the Trending page. Most stuff there is clickbaity garbage.
3. Actively curate your suggestions. If there are videos in your suggestions you don't care about, click "Not Interested" in the flyout menu. If you watch a video you like and you'd like to see more, subscribe to the channel, upvote the video, or add it to a private playlist.
My home page suggestions are limited to videos directly related to videos I've upvoted or channels I've subscribed to, except for the occasional time Google adds a "Popular music" or whatever section that is easily dismissed. Suggestions below videos are also pretty relevant.
One of my favourite channels is a New Zealander called Geoffrey Croker who is restoring his classic Land Rover, with dry humour, excellent lighting and cinematography, and good pacing. He just posted a video about the LR's engine that I haven't watched yet, but I'm sure will be great[0]. Rather than using YouTube's algorithm to discover new channels, I rely on comments like this one that I see around the Web, as well as when channels I watch call out other channels, the way This Old Tony[1] frequently does.
[0] https://youtu.be/KSjA3KJPwro
[1] https://youtu.be/qMrlyEreba8