I see this come up occasionally, and I thought I'd repost something I posted on a hoodoo list not all that long ago, in response to someone expressing curiosity over why someone would use sulphur or cayenne in a love spell. To their way of thinking, sulphur and cayenne are part of the crossing/hexing/icky family of herbs and minerals, from which you see them make occasional forays into uncrossing and protection work, and would thus "make more sense" as part of a breakup spell rather than a love spell.
Here was my response:
I'll tell you my theory on it, which you're free to reject 🙂 Where I grew up in Cajun cooking land, you think of cayenne as an irritant first, and then think of different ways to use irritants. One way to use irritants is to heat things up – a little cayenne can be a good thing. Think of old uses of Spanish Fly – an irritant for an aphrodisiac – or those herbal patches with capsicum in them that my Kung Fu instructor used to give us for healing. I think of cayenne in the same category as ginger and even cinnamon (only a hell of a lot more irritating). Then obviously irritants can be used to heat things up for less pleasurable or benevolent things as well (causing fuss and discord, running somebody crazy).
So I would think of it less like "cayenne is for breaking people up" and instead like "cayenne is for heating things up" and go from there in terms of thinking about how to use it. Is this making sense? I think this is the same way that sulphur can be used in attracting business, even though most folks think of it as a "drive away" or "cause trouble" ingredient. It's not always, though. I have a bunch of recipes for business scrubs from Mobile, AL, New Orleans, and areas around and between, that call for sulphur, to raise up attention and get a good crowd at an event or sidewalk sale or barbecue, and at least one "draw a lover" recipe that calls for sulphur, cayenne, and salt. Now, sulphur, cayenne and salt seem like a good "get the hell away from me" recipe, but at least on the Gulf Coast that same recipe has been used to get somebody to come back. I believe the principle is that a little irritant can be used to heat things up in a good way, given the larger context of whatever other work you have going on.