A Middle Ground for Erotic Book Marketing?

Is there such a thing as a middle ground? Marketing and advertising erotica appears to be such a subjective topic. From my reading the topic is also extremely broad.  I have read some "soft erotica" to some books which actively promote misogyny, rape or under age sex.  Who actually decides if your book is erotica or just romance, who decides if it can be advertised on their site. It is starting to become more clear on some websites, such as Facebook, who make their guidelines on what they find acceptable quite clear, but without actually reading the content of a book, who are they to decide? Obviously my book from the cover is clearly erotica, however if I changed the book cover to something less "adult" would more people be inclined to market it on their sites if it was re-labelled romance? I would suggest that the content of my book would happily fit into romance should I choose to re brand, however some of the content by others may be clearly classed as erotica. Admittedly erotic fiction is now much more main stream than it used to be, thanks to Ms James and Fifty Shades of Grey. Highlighting the fact that all erotic fiction writers are not all sat in dark little rooms wearing PVC and knee high boots, if nothing else. So why is marketing on main stream platforms still subjective? We face barriers that have no clear guidelines, when we do face clear guidelines they are subjective and can be interpreted. We have come far in the acceptance of Erotic Fiction, but I believe there is still some way to go yet as demand is far surpassing the advancement of marketing guidelines.  
I would appreciate your thoughts as always. Danielle