Several posters here and on other forums have described Sx/Sp and Sp/Sx as dark, intense, and sensual. I can understand "sensual" and "intense", but what do they mean by "dark"?
Oh, I'm dark, baby. Way dark.
Ok, seriously now.
My best explanation is that when compared with the so-secondary crowd, we are a lot "darker" and more raw. Sx/So's have a greater need to be seen and accepted, so their expressions of sexuality are more in keeping with accepted norms. They're also more overt with their sex appeal. They have big, bright, bold energy that seems to say, "Look at me! Look at me!". When they're really on, they're charismatic, dazzling, and virtually irresistible.
Self-preservation second frames things a little bit differently for an Sx/Sp. Issues of connection and intimacy take on a more urgent and visceral connotation. We prioritize our sx needs above everything else, and there's really no external moderating influence to speak of. At my core there is just this hunger, this need, for more, more, more. Like a fire within me that I wish I could feed until it consumed me altogether.
I think this is why we are perceived to be "dark". We are deeply in touch with those things about ourselves that are not exactly civilized or polite, and we revel in them. We smolder with them. But we take an equal delight in the uncivilized things in others. We want that
nasty. That realness. People can sense it, they aren't comfortable with it, so they put a label on it. Who knows, though? Maybe we are fucked up lol.