i'm laughing here, but really, bad farts are because of a lot of fat and spice in the diet and the body has the bacteria in the gut which work on those compounds and give you the bad results out the other end.
if i eat a diet of mostly vegetables and not as much spice or fats you'd not notice i've farted, unless you smell an invisible carrot. even with a lot of beans my body is used to them. you'd not know.
that was for the humans. dogs, nope, some are really bad and then they try to look all innocent but they know and you know...