Unless I am working in the US for a long period, my accent tends to be a moderated accent of unknown origin. (Or if I am with Germans, speaking English, then my English is an awful German-accented one)

I suspect that people think that I am British (even in the UK they are sometimes confused) Just this week a bartender in told me that he was confused when I asked for sparkling water 'because you are British'.

That may be why sometimes American servers think that I am a potentially bad tipper, and I think making that assumption is unfair. But I've seen my colleagues from the UK treated that way. I'm used to the multi-nationality, multi-lingual nature of my work and my personal life, so I don't generally stereotype based on accent, but in this case I think that it works against me to be generally soft spoken with an accent of unknown but slightly 'British' origin (not that such a general thing really exists)