It's in the Paizo era of Dragon, and what comes to mind is the image of a succubus(?) or similar reclining figure, in red IIRC. ANyway, there was something I was after in the article itself, but I don't even know what that's called either...
Yep, it was 306, thanks! Must be there's the same image between the covers too, or a similar one...
Aha! 'Betraying your Evil Nature' - that's the one. Thanks again for your help. I knew it was something to do with evil (duh) but, being a bit hungover, didn't know much else... :)