I am largely gay by preference now but have had some brief sexual relationships with very masculine women in the past. 
I’m in my 30s but first got to enjoying sniffing butt and ass licking a few years ago, with a dynamic, well dressed married business woman in France who got off on extra marital affairs with feminine men. She was incredibly kinky and liked to butt fuck me with a strap-on. 
The first time we had sex, late at night in her hotel suite, she stripped off her skirt, blouse, black thongs and nylon pantyhose and we did 69 and oral before penetration. I still recall her shapely buttocks as she squatted above my face and bent forward to suck me. I was so turned on by the intimacy. 
Desiree’s anus was so close to my nose and as she bent forward and the cheeks parted I could smell her long-day sweaty fecal odor, very ripe and amazingly smelly for a woman who had a Chanel perfume fragrance to her otherwise. She’d clearly had a shit at some point during the day and the silky thongs she wore and nylon pantyhose had trapped really strong odors in the crevice between her buttocks. 
I could not resist pacing my nose against it to sniff as she performed fellatio – it was arousingly stinky and I quickly found how much I enjoyed. She asked me to do anilingus (lick her anus) whilst she sucked me and the first taste was a little shitty but then as I licked and inserted the tip of my tongue into the opening of her orifice I relished it. Actually not that dirty really, Desiree was very hygienic and the smell and taste were just a natural earthy expectation (I briefly sniffed her thongs later and they smelt strongly of her pussy and ass odors). 
I licked her anus gently and she loved it, groaning from the stimulation as my cock pulsated in her mouth. Her butt fucking of me later was amazing and I got a chance to reciprocate by enjoying anal intercourse with Desiree. Hmm, so nice. I've really enjoyed this ass licking and sniffing aspect of sex ever since, especially with guys.