They come back with a different name but they are usually easy to spot 2nd time around.Its the sense of deja vu you get when you read the post then have a look at the profile or any links they put in.
21
bigal1
Westwood I would say they are easy to spot first time around and I think that LP are going to be looking harder at this forum for a while
Travelfish have long flagged correspondents from Vietnam because of the volume of this type of thing
23

westwood
Sometimes I've picked up on something not quite right and advised them of the rules but 2nd time, its more blatantly obvious.
Pro tip