Just for clarity, it's not really us that determines buying or selling -- it's an artifact of the construction of the platform on which we're trading + the method of constructing the combination. For my own [tiny, little] brain, it's just a dissonance that I don't need, to be working "negative" prices while attempting to "buy" a "bullish put" spread. Written via a different method, I'm suddenly dealing with *positive* prices while *selling* a "bearish put" spread for a credit -- just two or three less things I need to translate while trying to work. That said, for a broken-wing butterfly, I have to "buy" it for a negative (credit) price, and possibly then "sell" it for a negative OR for a positive price later. I can deal with that, because my mind can hold the BWB as [buy front 5W; sell back 10W] in my head.