The glass is cleaned after manufacture, so the assembly should be clean. Also it is glass, so no oils or residues from manufacture. My 1st wand was perfectly clean, inside and out. If it really bothers you, unscrew the glass cover and clean it with ISO and then hot water and allow to dry completely before reassembly. Be very careful when tightening the screw!! You break the glass doing that and you will need a new expensive cover.