I have not used Vapor Rub up the ass- But made successful use of it on a restrained man , using an electric massager to rub it into his tits - he was blindfolded in a leather bondage suit, tightly laced in and secured to the bench with many straps.
After getting him heated up, he was served lunch early - pork chop in a bag, straight out of the freezer on one nipple, a bag of frozen peas on the other.
He shot a huge load , made all the more enjoyable because he could not touch his cock and could not move his body. Impressive!
So I can only imagine what it would be like inside.
Maybe it should be applied to a baseball bat , and shoved up on that, so that your ass is well and truly coated before fucking begins!!