That's a really good point, didn't think of that. In that case, not sure...because you could also have people paying to upvote themselves from other accounts, which is just silly. I think, over time, machine learning could parse who is typically paying for a person's post, and then make an assumption that this is gaming the system and label that as an ad. Might be worth too a filter on trending/hot that defaults to "non-paid", but you can toggle to include ones with paid promotion.