I haven't really because I've had once or twice where I figured out that I'd been dropped by people I thought were friends and it really hurt. It may be that they didn't just drop me for personal reasons, but I don't want to ask. I don't want to put someone into a similar position who may read more into it than I intended.
I have had a few people who were offensive or just added me to spam their business ideas though, and I didn't feel bad about blocking or cleaning them off my lists.
As far as simplifying my FB friends, I've taken the time to add the categories and whenever I add a friend, I figure out which category fits them and make that part of adding them. Then if I need to find a more manageable chunk of my friends I can just go into Uni, Idaho, high school, New York, church, work, etc and pull up whoever fits in the respective group.