I'd like to think of these catfishers as still being proof of work, and adding value to the system even if that work is completely bogus.

It is testing the system and causing new approaches to pop up to deal with the hassle, which as Dan said is completely healthy for us. Creates more healthy work as a reaction.

Can't prevent all users from doing this, but as a community we also can't put a" lid on the bucket" at the sacrifice of getting new users to post.