Is there a problem according to any opinions of using creams and the like because of their treif animal content in the Glycerin of Sicha Kshtiyah:"anointing is like drinking"?
I heard a shiur by the OU's Rabbi Genack on this.
A custom arose among some Ashkenazic Jews not to apply anything specifically pig-derived on their skin, but otherwise, you can apply non-kosher items to your skin. Other than Yom Kippur, the rule of "anointing is like drinking" has nothing to do with kashrut today. It simply means that a Cohen who is given tithed olive oil (shemen terumah) for his consumption may also apply it to his skin.
One caveat: there is a category of prohibited items that is prohibited from all "tangible benefit" (issurei hana'ah), which would include smearing it on your skin. This category includes an item that was used in a pagan ritual, as well as meat that was cooked directly with milk. (This would only apply if the meat came from a ruminant.) I don't see any of this posing an issue with something like glycerin or most creams.