Bad hiring has a nasty ripple effect. It can cost a company time and money, and kill morale and productivity. That’s why many CEOs go to great, often extreme, lengths to make sure they’re getting the right people on board. Zappos’s Tony Hsieh, for instance, is so obsessed with preserving his quirky culture that he offers new hires $2,000 to leave a month later if they’re not happy. And such radical approaches aren’t as rare as you might think. Here’s how four other entrepreneurs are hacking hiring: