Some of these ETFs are subject to contango, backwardation, and good old "slippage" in the futures markets. The ones that buy options are also subject to time decay, a lose/lose proposition. One way to avoid these inefficiencies are the ETNs and the Paired Trusts like UOY / DOY. But those have their own issues. There is no free lunch. Really if you want very efficient leverage on the long side, just buy high-beta stocks without margin. On the short side, just forget it.
More Fun with Levered ETFs [View article]