Well, the dirt on my car or the oil inside my engine have little ability to effect my health.
I spend a good deal of time dry-firing my guns at home and if they're spewing trace amounts of powder in the air every time I rack the slide.. Also they sit sometimes a month, 2 months, 3 before their next use.
I find it a drag, but still clean em often
So you've never inhaled any exhaust whatsoever? Hmm interesting.
Also I think anything left on the gun would have little to no effect. Like you said, "trace" amounts.