I'm out almost everyday in Bangkok, and just once have I ever smelled weed. It was coming from a home along the Saen Saeb Canal. It smelled like the good stuff, and I certainly didn't get a 2nd hand buzz from it. Darn.
When your country's national sport is Muay Thai, you learn to fight with fists, elbows, knees, feet, etc.. If you're dumb enough to get in fights, using your feet as well as fists seems like a smarter way to fight.
I don't blame the seller for not wanting the used shaver sent back. At least you'll know they won't try to sell it again. Throw it away or clean it up and give it to someone you don't like much.