As some of you know, Amazon, and a few other sites, have been cracking down on covers, book descriptions, and content. (I know, content? Yes, some books are too dirty). It is their right to sell or not sell books so if you wish to remain with Amazon and not be tagged as an Adult, here are some rules to follow regarding your cover. As for blurbs or content, I can't help you there.
Frontal nudity of groin area, male or female (DUH)
Naked female torso--front view or sometimes side view (naked back okay, as long as butt crack not shown)
Side view of bare female breasts
An arm across bare female breasts or hands touching or clasping female breasts
Naked butt, male or female (discreet view of butt cheeks peeking out of bottom of shorts or skirt is okay; for example, Hot Tango by Sidney Bristol)
Naked people in a clinch even if they aren’t “fondling”
Position that implies sexual activity—woman kneeling with mouth near man’s groin (clothed or not); one naked or near-naked character lying on top of or straddling the other
“Fondling” or implied masturbation (hands touching groin even if clothed,hands grasping nude butt or grasping nude female breasts)
Some of these are Duh! moments but others not so much. I don't see why the arm across the breasts should be banned--nothing is showing. It's odd not to show or imply sexual activity for a cover that is meant to convey what the erotic book is about. With these rules, it's difficult for anyone to know that your book is erotica or romantica.
In order to make sure your cover is safe, I recommend a flower on the cover. However, if the content is very naughty, you will be tagged anyway and no one will be able to even search for you on Amazon. However, Smashwords (to my knowledge) does not ban books or covers so you can upload whatever you wish there.
Or, you can have two covers: one a solid color so as to not offend the Amazon Judges, and one very raunchy cover to promo. Best of both worlds.
These options aren't much fun but it's the best I can do under the restrictions.