> I've been thinking about up-votes/down-votes.

I don't have proof but I'm sure the amount of votes on eg. reddit (or perhaps how long it was on the front page) has an effect on search results; see the Comcast swastika[0] and Trump showing up when searching 'Idiot'[1].

0: https://old.reddit.com/r/funny/comments/403brr/10_months_lat...

1: https://thehill.com/policy/technology/397920-activists-manip...