I wouldn't have suspected a thing. (15 seconds in)
But wouldn’t a better solution be to get out of the place altogether, if you suspect that a drink might have been spiked?
If someone is targeting to drug and rape you, what does leaving accomplish? They can just follow.
In fact, leaving is likely what they want you to do. Drug kicks in, they pose as the Good Samaritan or friend taking the clearly drank-too-much person home.
A bartender could spike it and you'd be none the wiser. Always keeping your drink close and under your eyes doesn't always work.
The bartender is just about the only person who leaves a paper trail if they do this. I really don't think they're the likeliest of threats.
If you're worried your bartender is spiking your drink, the only logical thing to do is leave, not pull out your phone to run a test.
Jesus.
A lot of bartender pure "date-rape" alcohol into the drinks under the eyes of the customers.