One can make money buying or selling credit/debit spreads, as well as any other option position. But if you have a decent directional edge, why not just trade the underlying, or sell puts in a stock you want to own? If you convince yourself that it's a vol/skew trade, then shouldn't the further OTM strike (the one you are long) have a higher vol than the strike you are short?
If you are picking direction, while leaning on vol, why not sell a straddle and buy cheap wings.