What waiters can teach marketers
Waiters (either gender) interact with paying customers in a more freeform way, more often, than most service professionals. Here's one thing the good ones know:
If a customer tells you something, there's probably a reason.
"I'd like a water, with no ice please."
Now, while some people like to talk just to hear their own voice, there's probably a bigger reason the person said, "with no ice please." If you're going to be a great waiter, you realize that every single time a customer says something, you need to listen.
You don't have to do what they ask, but you do need to acknowledge it and respond to it.
Bringing ice in the water and hoping they will forget they asked is not good waitering. Or good marketing.