Ionic foot bath color and gunk? I need some honest answers!

OK people, I'm not exactly convinced these ionic foot baths really work how you all say. I've read through every thread here and wanted to get both sides of the story. I was particularly looking for people experimenting themselves on how the water color changes and how much "black stuff" and other stuff accumulates.  I'm not a nay-sayer but I want to point out obvious observations you guys seemed to fail to identify....

Some have said each person's water color is different, well, of course! No two people's feet will have the same gunk on the surface of their feet. From what I see, it seems OBVIOUS that remnants of soaps, lotions, foot funk n fungus, dirt, and what not that is festering under people's toenails will greatly dictate the "different water colors." Come on, that's obvious.

I also understand that these use stainless steel plates in the water, and people say when they first start using the baths there is a lot of black stuff, and then this stuff is not so apparent 10 or so times afterwards....  Did anyone think to replace the plates with brand new ones and see if the black stuff returns?  In my mind I think the plates are just corroding over time, at first they give off a lot of black stuff and later they don't as much. Something tells me that if someone replaces them the new ones will be producing a lot of black stuff again and the metallic smell would return. I need someone to tell me they have experimented with this!! Does anyone have closeup pictures of well used plates? Something tells me they look eroded and pitted, I believe that would explain "black pebbles and soot." 

I want to believe these things work, but I want to get the chemistry part of it figured out first.

Also, I haven't seen anyone truly say the water has been tested for specific metals and or toxins.  Please help me people, I need real answers!!! Not testimonials saying yeah it made my pain go away.  

Thanks!