It depends on what the person did. For example, if one was using a gaia gold cheat, they have a chance of being blocked from gaiaonline permanently.
utube
Well they don't tell you if they blocked you obviously, because it's a concern of privacy, but you would know if they blocked you if you sent a message or something like that and then if there's no response after a long time, then you know that they blocked you. :P
yes
Tektek.org
It gets blocked.
Chaos-programming is a good proxy
If you have blocked them, then you can't see them and they can't see you.
Usually it's the account, not the computer.
You can ask them.
nope
no they can not(:
You sure can, then if, in the future they unblock you, you'll still have them blocked.