I've seen this happen so many times and it's always so embarrassing. There's a lovely template that you can slap onto an article that says something along the lines of "this article appears to have been edited by someone with a close association with the subject." It's truly a marvel in how close it skates towards saying, "the subject of this bio didn't like parts of what people were saying, so they edited it to suit themselves" without saying exactly that. It's subtly brutal.
Fortunately for the feelings of people who edit their own wiki bios, I suspect that they probably don't feel the sense of shame that I would if I were in that position.