I would say that's subsumed into the cost of hiring someone. The amount of drama/overhead that is tolerable depends on how much it costs to replace them. If you're going to spend a 5 figure amount interviewing someone, as a recent HN submission pointed out, you have an incentive to try and fix a few issues before you give someone the boot. If you can just literally hang a sign up and open your door and get qualified people coming in to apply, then you'll probably get rid of someone who's the least bit of trouble.