Why can't you smell your own farts?

That's just plain wrong. I know for a fact that there is an unpleasant odor about when my sphincter passes gas. I don't even have to have a witness to know that it stinks. Other people apparently agree...

answers.kgb.com/why-cant-you-smell-your-own-farts/1975578 no longer exists
rebelcircus.com/blog/heres-like-smell-farts-according-science no longer exists

For those who want to deny reality though, there is a book out there which will answer this non-question: "How Loud Can You Burp?: and Other Extremely Important Questions (and Answers) from the Science Museum" by Glenn Murphy.

Not all farts smell. Much of the volume is nitrogen from swallowed air, and CO2 if you've been drinking fizzies. Neither of those smell. Certain foods tend to add piquancy to the fart - brussels sprouts and other cabbagy things are among them. If you've not emptied your solids out for longer than is normal, they will add smell. Certain bacteria show their presence too. As to smelling your own, remember your nose is at the front and your fart to the rear. If you are walking forwards, you will tend to leave it for others. Personally, I've always been able to smell some of mine when the wind was in the right direction (so to speak...).
https://en.wikipedia.org/wiki/Flatulence