"There are also leveraged inverse ETFs like SDS, which I have used at times. You don't want to hold them for more than a few weeks at a time because they decay, but for short-term trading they work fine."

Yes, that's the point - the idea is, instead of buying the short ETF, you short the long ETF.

They both decay, as you would expect an ETF to do, but by shorting the long, the decay works in your favor...