I know warnings are done as well, as a buddy of mine was going round and round with a poster and decided to spam keywords to mess with him. He found out that mods were not taking kindly to that and a message to him solved the issue post haste.
Part of the reason it solved the situation was becasue he had respect for how tough the mods job really is. Seems some like to think it is the most gracy thing a person could aske for.
To those folks I say...be very very careful what you wish for.