Yes, that's the assumption with ionic foot baths. It would be intersting to find out if indeed there is a correlation between these two ways of detoxing.
I have been doing these foot baths for a while and find them extremely beneficial.
With the color charts it is important to remember that while a good percentage is drawn from the feet, some of the color comes from other factors, particularly the black flecks.
At http://www.vitalityshoppe.com/id28.htm there is a good explanation of various other influences.