[plnewman]

I return the "how are you?" question with equivalent replies in shops all the time and if recipients were annoyed by it, I don't recall noticing. Being pleasant frequently helps me feel more pleasant. And anyway, I actually do hope they have a great day. I hope everyone has a great day.

[sbank]

I almost always ask how they are doing too, and never have I noticed (or don't remember) someone being annoyed by me asking.