I watch videos I'd like to get recommended while logged-in. I watch videos I'm not sure about in incognito/private browsing not to influence the recommendations in my account. If I find myself consuming that kind of content more often and would like it to be recommended to me, I promote it to the logged-in session. If I want to see less of it, I gradually demote it, including deleting YouTube history of videos of a certain type, and this acts as an indicator that I'm consuming more than I should.