Yelp has looked at using collaborative filtering to improve recommendation accuracy (this technology could handle the spaghetti case you mentioned), and it look

Yelp has looked at using collaborative filtering to improve recommendation accuracy (this technology could handle the spaghetti case you mentioned), and it looks like someone (probably an intern) published a paper on it. http://cs229.stanford.edu/proj2009/Fennell.pdf http://cs229.stanford.edu/proj2009/Fennell.pdf Looks like they didn't have sufficient data 3 years ago, but I imagine the prospects might be a little better now.