How do you know if she likes DATO? It's inversely proportional to length of the hair around her a-hole. The more she is licked back there, the shorter and less visible the hair is - really.....
I love DATO! I remember a really good session that started right after me and my guy got out the shower. We both took turns pulling each other's ass cheeks wide open and scrubbing them with dial, lol.
I get better sensations from DATO than DATY. I can feel the chills all the way from my back to my pussy. It's a great sensation when it's done right!
If you don't do DATO, rubbing some feathers or gently caressing her/his asshole with lubed fingers gives a wonderful feeling too.