I have to say I thought my cat was the only one that did this! I had a tabby that would do the exact same thing, and it was pretty funny to watch. I asked my vet about it and she said it is like a dog who scratches when you scratch him, its a reflex and nothing wrong with it. Many cats do this.
Sorry, but the visual in my head was just too cute when I pictured your kitty doing that!
It's probably just a weird reflex, especially if he switches sides when you do.
Our cats make this weird face when we scratch the base of their spines. Both cats do this. I can't describe the face, but it sure is funny.
I have a fat cat and she does the same thing - I think it's adorable. She can't really reach her back leg so I scratch her there - she loves it and starts licking her front paw. It's sort of "oh - it's grooming time" and you're grooming her - so she jumps in and does the same thing. It's just a cute quirk - no allergy or anything.
I think it's just an odd reflex. My cat licks his nose of you scratch the back of his neck or the base of his tail. Sometimes he'll set himself off while scratching an itch, and licks his nose the whole time he's scratching himself. I don't think there's a bit of harm in it, it's just a weird cat thing. They all have their quirks.
Licks himself on the genitalia or where? On the side you are scratching?
If the first case, the scratching is most probably very pleasant and it adds to his pleasure.
If the second - you are probably making his very very very precious fur tangled and also your scent gets on him. He is trying to clean the site and make it again perfect. I would not be concerned with this, if it would be unpleasant for him, he would show you. Cats need and prefer scratching and they also need to be very clean and odorless (they are hunters after all).
Just show your cat that you love him any way you can, he will tell you what he does not like.
My cat had a mild case of dandruff and she gets itchy on her back and right side. She is so happy when I scratch her itch for her, she licks either my hand or her fur. Happy cat!
Well, by touching him you got him dirty. No, seriously, when you touch him you are transferring your scent to him, and by licking that area, he is imprinting your scent onto his mind.
But also some cats are very fastidious about having their fur messed up, and by licking they are smoothing out their fur.
As far as your other cat not doing it, it probably does but not right away.
he lickes you so much to saving him from... well... anestesy that he dont lick himself, he wanna licks your hand has a proof of love