Wayne, anything labeled as "Rubbing" alcohol is isopropyl alcohol which is diluted with water and also with glycerine. Read the label and you'll find it says something like "...glycerine added as a rubefactant." This will leave an oily film on anything you wipe it on. That's what it's supposed to do - keep the skin from drying out. It is not a good idea to use it on scale models. (Other kinds... well, another story. )
91% Isopropyl alcohol, however, can be obtained in a 1-quart size from your pharmacy for less than $3. I've used less than a third of my quart that I got more than 2 years ago. The only other thing in it besides pure alcohol is distilled water. It's great for paint removal, cleaning, degreasing, and as an external antiseptic (its intended use). I've never seen any 99% isopropyl, and it would scare the heck out of me to use anything like that. Way too flammable.
Denatured alcohol, sold as a paint thinner (usually for shellac), is a very harsh form of wood alcohol, and is not, IMHO, suitable for use in model railroading.
Guys, all alcohols are not the same - they do not all come from the same source, and their chemical compositions and reactions can vary greatly. Do some homework before you consider using any chemical. Just because you can buy it, doesn't mean you should.