I was watching a Youtube video of Andy Burk on tying a Pyramid Lake Wooly Bugger, and he mentioned it is a good idea to grab some bottom mud and rub your flies with it to mask non-natural scents.
Later on I read an article on FAOL about scent trails and particularly that of human scent. The gist of it was that some people excrete more "L-Serine" than others from their hands and that it is a powerful fish repellent (along with bug spray, sunscreen, and some say even head cement).
"Smell Tracks - Fly Angler's OnLine
I have to admit, I've been real sloppy about it. I rub on sunscreen and mosquito repellent and kinda just wash my hands off in the water and wipe them on my waders. I'm pretty sure that for an animal who can find their way upstream to where they were born using scent alone, I am putting a big nasty Exxon Valdez kinda scent trail into the water, and getting it on my flies and leaders too.
I am going to get some biodegradable unscented soap like Dr. Bronner's and carry a little bottle of it with me to wash my hands with periodically throughout the day, any time I have handled stinky stuff other than fish. I'm thinking of also scooping up some mud and water from shore and carrying it in a small container like a film can to dunk my flies in and maybe rub on my leader.
It may not help, but I can't see any way it could hurt. Do YOU do anything to mask human scent related stuff on your flies?