I've ruined my FB account by liking every damn thing on the Internet that interested me, and since the FB Like button debuted I've accumulated over 1000 likes.
They now combine to fill my news feed with 99% noise, drowning out the posts from my real friends. Since I don't spend every second of the day monitoring my FB account, posts from real friends get pushed below the fold before the next time I login, and I miss them.
To make matters worse, FB has apparently disabled the Unlike button from the settings page that allows you to see all your likes in one dialog, which is apparently the closest thing to a bulk unlike available (you still have to click Unlike for each page, but at least they're all there in a convenient list).
So the only way to unlike stuff is apparently to visit each page, scroll down to the Unlike button in the bottom of the left menu, click it, then proceed to do the same for the next 1000+ pages. Not. I'm just switching over G+ instead.
Even with G+ I've made the mistake of subscribing to a bunch of shared circles, and there's an impedance mismatch between the topic of the circles, and the Public posts of the people in them. Even if I subscribe to say, a Python Developers circle, I still get people's public posts of pictures of dinner last night, etc., that is just more noise.
At least G+ makes it easy to fix the problem via unsubscribing, but what they could really use is the ability to add filters to circles based on hashtags. So if someone in my Python circle makes a public post that doesn't have #python, #pypy, #tornado, or some other python-related hastag that I've specified in my Python circle filter, that post won't show up in my feed.
But after having learned the hard way twice, I can guarantee I at least won't be adding more spammy businesses and whatnot to my G+ feed.