Maciej (HN handle 'idlewords') has an interesting take on this that I'm struggling to find in my history right now. The basic idea is that all of the data these companies collect is still ultimately useless in practice. We still don't have advertising that is even close to being relevant. But the data retains its toxic qualities (of being a database of every action I take on the Internet and some in the real world).…
Do you use YouTube while logged in? In my experience, the content recommendation on YouTube is the best. I've been learning about electronics and watching a few videos about it. Now YouTube recommends me new content and channels that are extremely relevant. My brother is into guitars, and his frontpage is all about that.
But, and this is a big but: YouTube doesn't provide the options to either dismiss any given suggestion, nor to block specific channels. There's sufficient crap on YouTube that both are essential. I've been campaigning for both features for some time now.
Google's recently implemented an account-wide blocked-users manager. It applies now to G+ and Hangouts, though it may move beyond that. "Google doesn't comment on future plans", as they're fond of saying. I have hopes.