Well, honestly they run the gamut from well done to holy shit this sucks. It's all pretty subjective, of course. The sucky writers didn't last in the business because there was so much competition. Andrew Offutt (John Cleve - Spaceways series and The Crusader series) and Robert Adams (Horseclans) both wrote porn books to put food on the table before they got big.
The most egregious thing I've found are the publisher's mistakes. Occasional shitty formatting, as though plenty of inter paragraph space makes up for a bad plot or the, Let's use LOTS AND LOTS OF MEANINGLESS CAPS TO TRY AND EMPHASIZE SOMETHING, then there're the ones with chapter issues (missing, duped, mis-ordered). On the whole, you can't beat them. If for nothing else the covers are pretty great ;-)
If you look at TripleX or I can't remember the other one, you'll have a good sense of what I have and browse covers.
My CSV file has these headers:
authors,comments,publisher,series,tags,title,#docno,#imp
If the situation involves rape or seduction, the aggressor tags are pre-fixed by "Ag." So, AgMom, AgSister, etc. If there's notation and no Ag character, assume the person on the left are initiating the activity. The vast majority of the tagging was based on the titles or the cover image. Even being old as fuck, I haven't managed to read them all ;-)
I started adding asstr player notation, but that's in it's infancy. I used forward and backward slashes to stop calibre from normalizing M/F and M/f, m/f, and m/F and similar combinations into one (M/F). Beast includes Zoo (non-pet: pigs, elephants, whatever) and I usually apply only it to dogs and horses, so if you see them both, somebody's getting diddled by more than Rover. Widows, babysitters, teachers, etc., all as you'd expect. There are some scene settings, but not many. You can usually imply them from the character tags (secretary, etc.).
