If a user is under investigation of voting irregularities, and has been charged as guilty, system takes back reputation earned from fraud voting. Should system take back those badges (Enlightened, Nice Answer and etc.) earned from fraud voting as well?
Personally I think it should, simply because badges are gained by cheating.
Note that this is completely different from normal voting increase/decrease scenario, for instance, user has an answer get voting increased over 10 (earn Nice Answer Badge) then voting decreased under 10.