It can be annoying when people you don't know choose not to give you the benefit of a doubt.

The worst is when you are in the midst of a group of people who speak the same language and the use their native language to communicate among themselves ignoring your presence.

Not only is this rude, I find it demeaning and racist. I really don't take offence when people patronise my English accent but I do get offended when they act racist about it.