I noticed a very strange phenomenon across Twitter and Google. It is immediately obvious that they are trying to guess my (your) interest and adjust their estimations over time. How nice of them.
The problem is that they get it wrong most of the time. For example, Google keeps nagging me with photography books on Google Play because (I think) I once downloaded a mostly-useless free eBook on Android photography. Twitter, on the other hand, probably because I follow Uber and car2go, keeps promoting tweets from car makers on my timeline.
As you may have guessed, I don’t give a damn about those things. Social knowledge graphs still have a long way to go, but I admit that accuracy varies in different context and sometimes it’s very high.
Google is particularly apt at serving ads and I must say that, those few times I notice them, they are in-topic. Other times they just throw a curve ball hoping I’ll catch it, like for Google Play suggestions.
Twitter is also rather good at suggesting new people to follow and potentially interesting tweets, but those mails always end up being deleted unread.