This is the kind of thing that would screen me out for sure. If you want a mock up for a site design I'm going to get the impression you're trying to "hire" 10

This is the kind of thing that would screen me out for sure. If you want a mock up for a site design I'm going to get the impression you're trying to "hire" 1000 unpaid designers. Unless you're talking about a 1 hour job, in which case you're getting something pathetic, this is just abuse by the potential employer. Further, you probably hired the 3 worst guys because they probably put in 50 hours on what should be a 1 hour design because they're so desperate for a job (further indicated by the fact that this ridiculous requirement didn't make them look elsewhere). That's also probably why it didn't match up with their resumes.