My barber is giving me a two vintage shave mugs one from the 1920s and one from the 1950s. I was planning on using them as my personal shave mugs. Tonight I was talking with an old friend of mine and he was saying that back in the day the reason everyone had a personalized mug at their barber shop was to prevent the getting of a type of rash that you could get if you used someone's mug. Is this true? Can I use these mugs or not? I know this sounds a bit paranoid, but does anyone else use vintage mugs?