The next question then I guess is how do you tell someone? I mean how do you really sit down with someone and say "I really like you, I really like hanging out with you, you're hilarious, you make me smile, I feel happy when I'm around you...but your personal scent just doesn't click with me."
I didn't get that deep when I told my "odd butter smell, no click" guy.
I just said something like...
"I like you as a friend and hanging out as friends. Yes, we tried some dates but it's just not clicking for me that way. There's no spark. I see you have feelings for me that way but I cannot help it if I do not. I am sorry. I'm still willing to be friends if you want that kind of relationship."
No need to tell him that his biochemistry, diet, whatever it is is causing a smell I can't click with for reasons I just cannot explain.
It's enough to say I just don't click for reasons I cannot explain. Not compatible is not compatible -- be it smells, religion, work schedules, hobbies, whatever.