Could you expand on "the work product isn't strong enough"? What do you check? A part from commented code, bad naming and bad indentation. Do you consider tests, or the architecture itself? Good writers = native speakers?

How many applications do you receive for a job opening? And how many do you interview and have them working on a project? Can you share some kind of projects you have them doing before hiring them officially? Is there anything a candidate can do to blow up a possible offer after your initial screening of applications?