My wife has a long term boyfriend, who has been fucking her for over 30 years. During that time I've tried all variations of creampie cleaning.
The first time is the one that produced the most arousal for me. It is seared into my memory, probably because of the intense humiliation I felt at the time.
We were having a threesome, and I'd watched him fuck her on the bed beside me. I was slowly, and carefully, wanking. After he had ejaculated inside her, and dismounted, she moved over and sat on my stomach. I could feel her and his wetness on me, and I quickly finished myself off.
Afterwards I told my wife how erotic it was feeling her wet pussy on me. She said that it had turned her on too. I suggested that next time she should sit on my face. She said "Even with his cum leaking out of me?". I told her "yes, especially because his cum would be leaking out of you". I said that I wanted her to deliberately wipe my nose into the evidence of her complete infidelity. And to make sure that he could see it.
So next time I was there to watch them fuck, after he'd ejaculated inside her, she positioned herself, knees either side of my face, facing my feet. I looked up and could see her wet pussy lips, with her pussy still fairly open, and his spunk just inside. Just as soon as she positioned herself over me she started dripping on my face. I could just see her boyfriend to my side,watching. Then my wife said "Clean me up. Clean up all the mess my boyfriends just left up my pussy."
She lowered herself down on to my face, and I started licking. I was so hard, and so turned on, but I dared not touch my cock, as I knew I would cum instantly. After a bit my wife started moving around, wiping herself across my face.
Across 30 years I've cleaned her/his creampie many times, in every position I could think of. It's most exciting for me when he can clearly see what I'm doing. Best is if he tells me to do it: "I've made a mess in your wifes pussy. Now lick it clean".