I dont think it quite works that wayeither. However the skin can obsorb certain ingredients (hence why those creams and oils work) ... But this method is also used in compresses. In example boil some herbs then dip a piece of cloth in it. Try to get some of the water out (its not supposed to be soaking wet) and quickly put on the place and keep it warm and covered. Then just let it sit for 20 min. Afterwards take it off.
Its said that this cloth should not be reused or if so it should be put in boiling hot water and washed before reusing again.
Remember oil pulling? On the gums? Same principle.
Anyway in conclusion. If the ingredients get taken on through the skin which then causes an effect in the area yes it would work. Through the bloodstream these toxities would have to be released and it is then adviced to drink quite a bit to a lot of water so these can be drained by the kidneys.
Oh by the way, there are also cold compresses and these are usually used on things that feel hot like ie sunburns (note: ROOMTEMPERATURE COLD NOT SNOW OR FREEZING COLD) or swellings or inflammations (if the person feels it is relieving) or to get a very high fever down (but more likely feeling too warm in summer) some say to cool the feet as the temperature of the feet regulate the bodies temperature or something like that.