For what reasons do you block or delete someone from facebook?

All of the above.

But eventually so many people were doing these things, I just gave up on the fight and deleted my own Facebook.

That, and the privacy issues led me to abandon Facebook.
They kept resetting my privacy settings every time they changed the layout so that everyone could see everything, and the stuff that I "deleted" kept coming back.

I've been gradually deleting a lot of people. Sometimes because they're statuses and stuff are annoying. Sometimes because it's pointless being friends with them on there. I'm fairly sure I know everyone on my friend list thing, but some of them are not in my life at all anymore (and weren't a part of my life massively in the first place). I'm planning on getting my list down to people I actually use Facebook to talk to, and who I know well.

It looks like you deleted my comment. Were you offended that I think blocking people is an immature way to show someone you are mad at them? What do think you're showing by blocking and deleting people and their comments? It just shows insecurity that you cannot be upfront with them and instead avoid the issue.
I apologize if you didn't delete my comment and it was a glitch.

I am lucky to not have many people on my facebook so I only delete people who were a-holes to me IRL.

too many game requests and useless event invites

I delete people when I'm in a bad mood, when they don't say hi when they meet me and yet comment on all my statuses and I delete guys that I've dated out of respect for my boyfriend.

i only block people on facebook who are girls and only add you to chat me up i do not need that is annoying that and people i do not know i hate that its ok if someone else in my friends list knows you, i know you, or someone i have know online for years but i do not allow complete strangers.

If they start drama with me or try to put me down

I don't block or delete anyone, cause I don't use fb. I use it very rarely. Only blocked one girl (Who I know in real life). Reason: She was an idiot.

If they like and share those stupid pictures from those stupid teen pages, I will strongly consider unfriending them. The bizarre thing is, all of the people I've unfriended for this reason were adults.

If they start drama and arguments over asinine reasons and drag me into it, I will block them.

If they say something horrible, I will block them.

Sometimes I will unfriend people just because I don't like them.

I no longer have fb but I would delete or block girls that mention their bf all the time.

Everything you mentioned above. I find myself either removing them or hiding their statuses from my news feed.

All of the above are reasons for me to delete someone. Unless they are a good friend of mine, in which case I'll just 'ignore' their posts.

I just unsubscribe/ hide all stories from people when they get to be too annoying. I'm too much of a stalker to delete anyone, especially those annoying girls with hot bikini/party pics.