No. The skin readily absorbs compounds, including any toxins coming from the foot pads themselves. The only known compound that will extract heavy metals by trans-dermal application is a chemical called DMSO, and foot pads do not contain it. There are other compounds such as EDTA (and natural food-based substances and supplements too) which must be taken internally to be of any use. Foot pads do not contain any of these things either. The foot pads simply contain chemicals that turn them dark whenever they are in contact with moisture. This is to deceive customers into believing that something must have come out of the body to make the pads "dirty". The fact that the discoloration rate changes over time for the pads is a likely indicator that their chemicals are aggravating the sweat glands.
During a real detoxification, a person usually feels worse before feeling better. In some cases, he may experience flu like symptoms, and substantially increased allergies, especially during rapid detoxifications. This is believed to be due to the fact that the detoxification process frees toxins from the organs and/or fat cells so that the a great amount of stored toxins are freely moving in the blood at levels greater than ever before.
The amazing thing is that the FDA is allowing these while suppressing real alternative therapies, so the game plan must be to allow frauds like this in order to discredit alternative medicine. Members of the alternative health community are currently working to stop this deception.
This answer is locked because corporate interests are using it to spam and promote these products.