If you're going to reorg a block because its content is evil, or just doesn't obey your favorite new soft fork rules, please put its hash in a coinbase OP_RETURN of your alternative block.

That proves you saw the block but chose not to accept it. As opposed to just having missed it, as with a typical stale block.

Call it a Bad Uncle block?

You could even do this with weak blocks (reduced proof of work) if all you have is a BitAxe.