There have been a number of known lib posters and being a lib isn't cause enough to be banned or suspended from FR; sometimes the devil you know is better than the one you don't. Some banned posters quickly come back with a new alias. There was one woman who some Freepers quickly detected each time she changed her guise. They even posted the full roster of old names.
I've seen a few posters get banned after a year or more of activity. Some other posters go dormant for awhile and then go through a heavy period of posting activity.
Some just start offensive threads and never rejoin the discussion.