My own theory that is probably not scientifically true as to why some farts don’t smell and others do to varying degrees. 

I read somewhere (and didn’t bother verifying) that little doodoo particles are released into the air during flatulence. 

If that’s true, our bholes are like a chamber of poopy sludge. If your chamber is full, you’re gonna release microscopic dingleberries into the air and they smell exactly like what they are. 

The seemingly odorless boofs…must have less mini turds flying about. Or perhaps the poopoo chamber was emptied before the butt whisper. 

Again, this is probably not true.