I don't know. It may have something to do with the dog's individual nature. I feed my three the same kind of food, bathe them on the same day, etc.. but for some reasons, Muffin's always the stinkiest in all counts!
I haven't ever noticed Domino or any other pit having particularly smelly gas.
The worst is my friend's great dane when he's nervous (which is often!). Ugh it's so awful. Oh and my old roommate's boxer was really terrible too. My roommate was constantly feeding her rawhide treats and it gave her such gnarly gas. You'd hear it, smell it and then the dog would leave the room - offended by her own stink.
My rottie Harley had the worst farts ever. He could clear a room and even wake me up from a deep sleep. And then there was the time we went camping and he got sprayed by a skunk. The ride home was the worst car ride EVER.
I dunno about pits having bad gas, but drmom reminded me that one time I was driving home with Bruno, and it was pouring outside. He totally ripped the nastiest fart ever, and I couldn't even roll down the windows. It sucked majorly!!!