This reminds me ... several years ago, I changed dentists. The guy I ended up changing to was a sort of no-frills, low budget dentist. (That may explain all of the fillings I needed when I later switched to someone else after this guy just suddenly closed his office one night under the cloak of darkness.)
Anyway, the first time I was at my no-frills dentist, after cleaning my teeth, he handed me a cup of water to rinse my mouth. After complying with the rinse cycle, I automatically turned to my left to spit, only to have his assistant scream at me because she was sitting there and he didn't have one of those spittoon sink things.