compare this with the technical interview bomb of demanding you write a full blown program right fuking now, complete with tests. Which one do you prefer?

I prefer to describe a bug in details, but it is hard to come up with the details on the fly without prior preparation

Writing the program. Recalling a bug for the purpose of impressing a stranger does not sound fun.

For past experience I reviews like this it's a good idea to give the candidate advance notice.

Ok, but why do you think you should be hired in that place though? :)

Agreed. It's a great interview question. For a story-telling position.