Clear mouthpieces, unless you are eating as you play (thats a big NO NO!!) dont get disgusting other than te fact you can see all the spit. I have a pomarico crystal mpc for my alto, and its a nice, dark classical piece. A freind of mine has a clear Conn Comet piece from the 40s, and a Dukoff clear super power chamber(like the one on saquest a while back if any of you remember)
Both play great, and dont look any nastier than a Jody Jazz or a Runyon.
I also have a clear crytal and a clear plastic mpc for my trumpet - same results on the look; and the same goes for another freind's cleat Tiba mpc.