How's your English doin' ?

Every day that goes by, I wonder how good my English is doing. It's always a worry as we speak all day long in both English and French with visitors. For example, at the start of every English guided tour, I'm worried that a visitor will comment on my accent or on the mistakes that I might make.
2 minutes go by.. then 10... and I just forget my first fears. So far, no one has said anything but I guess we all agree that a visitor commenting on the standard of my English will be surprisingly stupid and culturally self-centered. Most of our visitors are just really glad we speak English.