I do use DEP about as much as I do alcohol.
I use the alcohol tinctured castor as an ingredient in lures. If you use it for a rub set for canines or cats, it still works well. The alcohol does evaporate, leaving only castor smell. Take a piece of cardboard and paint some alcohol tinctured beaver castor on it. After it dries, indicating the alcohol has evaporated, smell the cardboard. You should notice a nice castor smell.
So, would adding something like glycerin help hold the sent a little longer or would it just dilute it or is that what Mr Jameson is referring too?