I had a friend who wasn't a BNF in larger circles, but was definitely a BNF on fanfiction.net. However, a lot of people thought her fics were pretty bad and that her OC was a Mary Sue, and she got a lot of nasty reviews; she also got featured on a few popular spork communities. So I'm glad I wasn't a BNF, because I know from her how much bad shit you can get thrown at you.

(I mean, sure, her fics weren't... great, but she was hurt by how harsh some people were, and would've been humiliated if she knew how infamous she was in the spork world.)