Replying to Getting Un-friended on Facebook

I'm not a big Facebook user, and I hardly ever post anything. Literally never add a status and hardly ever add pics or anything. Sometimes I'll "like" or comment on a picture or status, but for the most part, I shouldn't be popping up on peoples news feeds that often. However, every now and then I'll notice someone who I haven't talked to for awhile unfriend me. I know, the obvious is that they just unfriened me because they haven't talked to me in awhile. But why would they even bother? Since I hardly show any activity on Facebook, I won't ever be showing up peoples news feeds. When I delete someone, it's usually because I'm sick of whatever crap they are constantly posting. I'm just concerned that maybe I clicked on a bad link that hacked my account and has me posting crap without me even knowing it. Cause sometimes I've seen suspicious looking vidoes posted by someone who wouldn't be interested in that video. So is it possible that I clicked a bad link some time ago and has me posting crap on peoples walls?