Today I have found - in the Votes Cast statistics on stack overflow - that my votes was decreased by 10. At the begining, I thought I was mistaken. Then, I realised that the statistics says that I have casted 0 down votes. That can't be true if I have the Critic badge.. right ?
It can be correct -- if you cast a downvote, wait a bit, then undo it.
Badges are generally never rescinded, so you would have critic with no downvotes in that case.
(File under: yet another in the litany of reasons that vote undo windows are hugely problematic..)