The worst ones are the ones like the one mentioned a few pages back, who work their way in and stay. They go to meet-ups, they form friendships off MN, and then are revealed as fakers. That must feel, to the posters having been taken in, like they've been violated in some way. These people build their stories up for years.
The one I remember from another site was married, 1 child, a moderator on one of the boards. Very good friends with a fair few others, one went to stay with her regularly in Scotland. All came out in the wash when she had a miscarriage. Except she didn't. Because she was a single woman, with a child, living with her mother. When her board friend called her to see how she was after the m/c, her mother answered the phone and said "Oh, so you're X, you're the reason why I get sent to stay with my sister twice a year".
Numerous others like that, and worse, on here. Always at least 2 fakesters going for the long haul at any given time.
And of course, most of the time their stories aren't going to raise any eyebrows at HQ. Why would they? They spin their yarns, have their own support threads, gullible fools (who frankly are so stupid they should have their internet privileges revoked) continue to do the "saviour" thing on the threads.
And it continues to be the trollhunters who get the grief. Mad world.