Seriously, if I unfriended everyone who posted inane junk on their wall, I'd have no friends. It's easier to just quit Facebook.
That worked for me. Oh, by the way, here is my 243rd post proudly declaring that I'm going to the gym to work out today.
My pet peeve is the salespeople. One of my former FB friends was a travel agent and sent daily status updates promoting the best travel deals, along with his agency's web site and phone number. One shamelessly promoted his wife's Tupperware business, and another used FB to advertise his home-based scented candle franchise. One friend even posted "Anyone interested in a two storey, four bedroom house?".
...and don't get me started on those stream-of-consciousness folks who contemplate what they thinking of having for supper tonight... and those who actually post photos of their meals!