—never put your mouth on the glass.
You’ll go into commercial auditions where they’ll have dinner ware, forks, spoons, glasses.
Never put your mouth on any of them. They’re gross. You don’t know who’s been in before you, or when everything’s been washed last. Many casting houses try to be good at keeping things clean but they’re busy environments and things get forgotten, left behind, or shoved into the prop closet for later use.
When I’m session directing I’ll put a piece of tape on the rim of a glass as a visual reminder to people not to put their mouths on it.
People still do.
In an audition, if it’s a short glass, and I can get away with it, I’ll put my thumb right at the rim so my mouth will go on my thumb instead. If it’s a tall glass, and that would look weird, I place the rim of the glass between my bottom lip and my chin so I can still make the drinking motion without it being near my mouth.
Never put your mouth on the glass. The world is already enough of a germ factory.