well the effect I heard is that even people who don't buy the chicken (ever, they just aren't chicken buyers) buy more of everything else due to the smell. So the store doesn't need to sell any at all, it just needs to be there. Though come to think of it this actually wouldn't affect price (because that smell effect would hold true if it's too expensive, right?) so perhaps it's a combination of both your effect (which affects chicken buyers) and the one I heard about (which affects non-buyers).