I'm still active on Reddit every day, for the crypto subs and Polandball. I don't see a lot of ads compared to other sites, maybe because I don't live in the US. Outside of the popular subreddits, I don't notice a lot of fake upvotes - maybe I'm naive :) The most annoying thing is the karma farming bots that are copying parts of popular comments and posting the result in the same thread.
By the way, I think the number of fake accounts is much worse on Twitter. You can buy followers, retweets and likes. And Twitter is struggling to show a high number of active users to their advertisers and shareholders, so they're not eager to remove fake accounts. Users feel flattered when they're followed by spam accounts, so they're not likely to complain either.