Sure you can, but that's what everyone is thinking so to make the long story short there is no free lunch.
A few months ago it seemed like they were giving away money on Sears' reversals - you could lock in over 20%. Sears shares were hard to borrow, but there were some available at IB. So I did a few reversals just to see what would go wrong. Everything seemed perfect - until on a tip I dug deep into my account info on IB and found they were charging me about 35% for the borrowed stock! Chalk one up for the "no free lunch" crowd.
It's described in this post http://www.elitetrader.com/vb/showt...highlight=mighty+sneaky+outfit+ib#post2057096 In fact, I highly recommend that you read through that thread, which chronicles the follies of a few of us "free lunch curious" folks who tried to take advantage of this seeming fool-proof mispricing and ended up getting shafted.
Thanks for chronicling your saga of short interest fees by IB (I read your link). As a former member of the "free lunch" crowd, I always wondered why those can't miss arbs never worked out as well as advertised. In my new life, I carry a lot of short stock and have struggled to figure out the math behind the fees. Now I thnk I'll just lie back and enjoy the screwing.