It's based on what you watch.

My recommendations are entirely in line with what I watch. I never need to check channels i like for a new video because they automatically get recommended.

If yours is a sewage firehouse, are you logged in? Or are you sharing your account with family members who watch what you consider "sewage"?

Mine's still stuck on recommending me culvert uncloging videos after I watched one way back. I switched to Freetube and imported my subscriptions, and that made things much better, since now I can't even accidentally see what my recommended videos would be.