I had an extremely bad experience with Developer Auction. Ultimately using the site got me fired from my job and the team at Developer Auction was extremely non-responsive/uncaring about it all. Matt Miszewski in particular was extremely callous.
It's pretty common for someone to be fired when discovered interviewing elsewhere. Usually, though, they draw up one of those horrible "performance improvement plans" and you'll be able to move on before it closes.
Worst is when you're trying for internal transfer and get PIP'd because of it. Then you have to get a job elsewhere, because the PIP fucks up your internal mobility.