Ever wonder just exactly how it is that somebody can actually have enough working brain cells to enable them to function in life and still expect people to fall for even ONE of those "get-rich-quick-selling-the-secret-to-this-plan-on-ebay" schemes? I am not a hamster, the only one that can ever expect to be shopping for gold watches with the proceeds of the thing is the prime mover.. the guy at the top of the food chain sending out all the spams. Everybody else earns progressively less and less as the market saturates itself.
It's the same thing with any other flavor of spam. Anyone who was actually needing Viagra or any of those others would, I'm sure, prefer to get the stuff from a legitimate supplier instead of some 3rd or 4th party question marks who could be selling anything from the real thing to chalk dust.