They're not even anything to look at are they? Imagine lying in the bath staring at a row of old bean cans with the dates still stamped on and a foul mixture of Yankee candles' greatest hits billowing out. Not really my idea of a magical diy home spa.
(I sometimes re-use cans - especially the catering size ones, as garden pots. Make a few drainage holes with a drill or bradawl - DO NOT ruin a perfectly good screwdriver - and pot up a couple of supermarket primroses. I'll give you that one for nothing Jack.)