Back when I used to drink martinis, I was of the opinion that if they poured the gin (no label loyalty here) while waving the stoppered bottle of vermouth above it, that was fine.

I liked the flavor of dirty martinis, until a friend pointed out that the bartender was probably using the brine in the garnish tray. Which was also okay, until we watched a sweaty-fingered patron wander over to the bar and grub out some olives from the garnish tray with his hands. No more of that for me.