Pretty interesting thread.
I'm super smell sensitive - farts definitely don't flip my nipple nuts at all - but I can sorta get where the OP is coming from. Not so much from a being turned on perspective but, to me, it's something like seeing a hot guys hole, I'm not so much turned on by an arsehole but - I like that I know what that guys hole looks like.
It's knowing something about someone who's in a league of their own that is super secret or personal that now I know, not sure why that's a big deal for me - but it is.
Rather than it being a turn on - I like knowing things about super-hot blokes that give you some intimate knowledge of them that also levels them off a little.
Same goes for farts in a way - Most times, farts pretty much turn me right off - even from decent looking blokes. But there are some guys that I not so much obsess about but find so unworldly attractive that knowing what their farts smell like or what their arsehole looks like - brings my view of them down to earth a little more that helps me connect with them better.
Its kind odd and the best way I can find to explain it would be - I'd love to know what say "Channing Tatum's " farts smell like not because his farts would turn me on - but because it would be something that would humanise him to me as well as it being something intimate that I would then know about him.