Hmm… my cats are both female. I wonder if that has any effect? Both spayed, as well, but my oldest had gone into once before.
And only one of my girls sticks her little bum in my face. As **Indygrrl ** has mentioned, it is not a pleasant thing. I try to scratch her behind her ears as much as possible. I can stand a little cat breath. Cat musk is a bit too Chanel for me.
And once, she even went into heat.
hehehehe at Chanel. [I got the ‘heat’ part] 
My vet taught me to rub/scratch the area in front of the tail on my two absolutely feral young cats - and she taught me to force pet them wrapped in a towel to create a relationship. It worked. Many cats only want their owner to do it and react badly. But some cats unfamiliar are confused and act funny - I go to places and do it to peoples’ cats and the cat goes (happily) berserk and the owners get rabid that i have upset their cat - which is usu. expected to sleep, eat & look out the window and nothing else.
My cats all love it; it induces “Bum in the Air” - aka Elevator Butt. (My kitties do not use such vulgarities as the word “butt.” Sniff.)
It used to be that Booger the tomcat hated it, so I’d do it just to annoy him. "Cept I’ve done it to him so much now that he’s beginning to like it.
I don’t know about Audrey, the calico Maine Coon. She avoids me like the plague, and I’m fine with that.
Does anyone else’s cat turn into a licking fiend if you scratch there? Two of mine start frantically licking the air or your arm or their own foot if you scratch them.
Quill (apt description of her tail) engages in the elevated posterior mode quite willingly. I’ve sometimes rubbed the base of her tail so long that my arms start cramping.
But there’s a limit.
She’ll be purring away, but the first sign of danger comes when the ears start turning backwards. The tail then starts switching back with tip looking like the rattler of a rattlesnake. Wise men would cease and desist, but I tread where fools go. Suddenly, she’ll spins around wrapping her paws around my hand and starts nipping hard with her claws extended digging (sometimes she draws blood, sometimes not), while her rear legs pounding on my forearm with mock scratching. Then she jumps away, sits on floor with her back to turn to me; the tail and ears still showing offense.
About five minutes later she jumps up for another treatment and the cycle starts all over again. My wife is both humored and disgusted by this behavior and routinely calls her “Kitty Slut”.
Ashes, Ashes, My Ralph loves to have his ears twisted and pulled. He also loves butt scratches and the kind of spanking-petting at his boodie.
As if a cat owner has a choice! 
I love this line and I wish I could use it but I can’t see encountering a situation in which it would be socially acceptable. 
Yep. She does. Licks anything nearby.
hehehe user_hostile. My cat does the same. And she bites my hand too. Since she’s a tiny cat, she has tiny teeth and nails, but the amount of blood coming from my arm sometimes is amazing.
Yup, mine does. Some times, for fun, I’ll scratch her till her tongue gets going, then I’ll stop, the tongue’ll stop, I’ll start back up, and the tongue’ll go right back out, licking the air. She’s so damned cute and helpless when that happens. 
In the name of science I tried this again last night. I can confirm that they most certainly do not like it.
'member this little guy (8 pics down)? He liked the butt scratches.
You guys do realize you are all masturbating your cats, indirectly. Eeew.
You think that’s bad, there’s one Doper who perfomed analingus on a dog.
I saw that thread. That was *one * Doper. These are a bunch of people, all doing the same thing.
Hey Tuckerfan, haven’t gotten an e-mail from you in a while. Everything all right?
Seven cats in my household, all in favor of butt-scratching. Eddy gets so into it, he does a sort of shoulder-dive into whatever he’s standing on as his nether regions soar.
Most of them adore belly rubs, too, although the real fanatic for belly skritches is my 23-year-old Quarter Horse, who’ll bulge out his side at any available human, and paw in frustration if his invitation is ignored.
Perhaps, for unspayed female cats in heat, this could be considered masturbating your cat… (or rather, teasing her) But in most cases it’s not.
It’s a condition called feline hyperethsia. You can read about it on page 2 of this article.
and here
My cat has this… the skin rippling, tail swooshing… doesn’t like to be pet along his spine or the base of his tail. And the hallucinations… I’m always teasing him about chasing ghost mice.