I can't say anything good/bad for fandoms overall, (except Twilight, that fandom sucks) but I can say something good/bad for PARTS of fandoms.
Best:
Bronies/Furries that are intelligent and don't shove their fandom down others' throats like a religion.
Religious people who are... well, the above.
Pewdiepie/Nova/Toby/etc. fans who are intelligent.
Worst:
Bronies/Furries that are idiotic and shove their fandom down others' throats.
Religious people that do the same.
Pewdiepie/Nova/Toby/etc. fans who act like 6-year olds who need a mental hospital.