My search illuminated that I tend to use it more in regards to a character "Rapey Dude" or a thing "Rapey backstory" than a general description.

I think "unnecessary" is bigger for me than "lots." It's just easier to roll over one time (though a book by Nora Roberts I read had a single deeply unnecessary rape scene of an unnamed character and no other rape, and pushed the author onto my do not read list forever).

(I also find that "unnecessary" and "uncritical rape culture" often to come as a bundle.)

There are certainly works with a fair bit of rape in them that I've liked, and liked a lot. Fifth Season is a recent example, but there it seemed to be an important part of what the author was trying to say about the world.

It's often difficult to pin down the balance between aura of rapiness and well handled.