Grab a cheap Corelle bowl. For whatever reason, soap samples stick real well to the bowl when mashed down. And, since it's glass, you can stick the bowl in the dishwasher when finished with the sample and, viola!, no residual shave soap scent remains in the bowl.
Edit, this is what I use: http://www.amazon.com/Corelle-Livingware-Cereal-Winter-18-Ounce/dp/B0000CFTDC/