Good question. I'm cautiously skeptical. The reason is that when I have smelled what I suspect may be bigfoot, there have been no other indications of their presence. When I have seen them, found tracks, been whooped at, exchanged whistles, had things thrown near me, and during the camp visits backpacking, I've smelled nothing.
Some here may recall my account of bumping into a strong, acrid fecal smell on the mountain in 2007. A few years ago I was out of town in training for a week. I was wearing Merrell Trail Gloves walking from the hotel to class. One day I bent over to take the shoes off and I got hit by essentially the same smell. My first thought was that I'd somehow unknowingly "soiled" my pants. :( :( :( However, it was coming from the shoes. They are plastic and don't breath very well. Apparently they retain foot moisture and it ferments. :( :( :( Unpleasantly. So .. I have to leave what you're suggesting on the table as a possibility. If that is the case, I think it most likely to be a result of a startle reaction, not something under conscious control nor something that happens if situations develop slowly.
MIB