Personally that would not be something I would want to buy, though I agree that we all probably have a big collection of stuff that we will never use. I tend to give such things away to girlfriends to try out. I also keep a big basket in the bathroom for guests in case they've left something at home. Maybe you could get a group of girlies round to your house one evening with their collections and a bottle or two, and agree to swap or sell for minimal amounts? I would certainly be happier to see the person that had tried it out and would find it helpful to know what they were expecting the product to do and why it didn't work for them.
It's amazing how many products I've thought were useless but girlfriends cannot live without!