I haven't had anyone say the term 'roach coach' to me in thirty years, and the last time I heard it used was in reference to the lunch truck that parked outside of my high schoool in the mid-60's.
Health Department inspections and mandatory food safety instruction have made that term obsolete.
I wish that were the case with me. Any time I tell someone about my ezine (Mobile Cuisine Magazine), the first question raised is, "Oh, you mean "roach coaches"?" Unfortunately too many people in Chicago have yet to try the food coming from gourmet food trucks since our current legislation prevents them from preparing food on site. Even the few trucks we have that sell pre-packaged food get referred to with the RC term.
The way I try to explain it to them is to take the old "roach coach", add a chef and gourmet food with the same cleanliness of most high end restaurants. I notice a glimmer in their eye, then watch as the light bulb goes on..."oh, that does sound good."