Why do farts smell horrible to others, but not to the farter?

If 2 people be sitting next to eachother and they both farted (and kept it silent), would respectively person imagine the farts were their own, or would they be repulsed because they would know how to smell the others fart?Why do farts smell horrible to others, but not to the farter?
This question make me smile. Honestly I don't think any would be repulsed unless it was really unpromising (as you said, the farter usually doesn't mind they're own, but sometimes I actually grain like I'm gonna barf at my own if I've have way to much fiber recently) but both would be extremly red.
lol