Oh so all of us users have oscilloscopes and frequency generators of professional grade sitting around in our garages somewhere. Where do you live --geekville right next to the whos?? I have no such way--and are you even testing the human frequencies--those are pretty high grade scopes that can. And if you're not worried, why would you?
Have you bought and tested a zapper within the last 6 months, and if so, why are you buying zappers since you're so sure they don't work??
And still I try to imagine that somewhere, you're capable of rational, logical thought, so obviously wishful thinking does not one whit of good. And age is good--makes you far less likely to fall for stuff (since when you were younger, you probably did) and now realize quackery when you see it.