From what I have seen the Kobo recommendation system is the worst one I've ever come across and the internet is full of them. For whatever reason the majority of books recommended are 'romance' type novels. I've never read/bought one and routinely mark them as not interested. The recommendation engine doesn't seem too concerned with my choices and so I've come to just ignore it. That's Marketing!
Since the recommendation engine seems to be driving the firmware update frequency you'd think that it would actually work better.