I have had no direct experience, but think I have a book or two that address some encounters. I'll look for them & pass their names on to you.
If you don't mind my asking, what is your experience and interest? You can reply directly to me if you don't feel comfortable talking about it in the forum.
I have no personal expereinces myself, but I have heard about them. I wanted to know if they are true, and if it's really such a bad thing to have them visit you.
Here are some books you may want to check out. The first three I have read, & they deal with the subject in an historical, rather than current day sense. The are also out of print (try a used book site like Alibris.com). The last two I have not read yet. They relate to the more practical applications, and can be found on Amazon.com.
Eros & Evil by R.E.L. Masters
Magica Sexualis by Emile Laurent & Paul Nagor
Sexuality, Magic, & Perversion by Francis King
Summoning Spirits: The Art of Magical Evocation by Konstantinos
Sexual Alchemy: Magical Intercourse with Spirits by Donald Tyson