That is a warning I don't ever need to be told.
I had a fella show up at the house one sat looking to have his A6 worked on. I told him it was a gussied up passat with chrome radio knobs and that he better get it the F off my property while he still had the ability to do so under his own power.
I should mention he was a bit of a "better then everybody else" type, and didn't like the fact that I pointed to my driveway that is full of Porsches and a token Mercedes, you know real German cars