In the past I have wondered about the ionic foot baths too.
Curiosity got the better of me and I went ahead and took a months sessions to get my own opinion. The technican explained that the toxins are drawn from the body via the sweat glands in the feet. I didn't really feel any thing different, it was relaxing but rather pricey considering I didn't feel any healthier.
Are you familar with the moreless protocol for foot baths? It is suppose to draw acids from the body and the cost factor would be a lot cheaper.