Chilul Hashem depends on what the average guy on the street says about the fellow. See Yoma 86, Mi shediburo bnachas im habriyos, Mah habriyos omrim alav, etc. It doesn’t say what do the gedolei hador say about him, it says briyos.
For example, people who make a big minyan on the plane, and block the aisles and the bathrooms and crash into all the other passengers and crew are making a chilul hashem. People think it is rude. We don’t say, too bad, a Jew is supposed to daven with a minyan, tough luck to all the rest of you. Rather, chilul hashem depends on the onlookers.
As far as getting asked out by the Pizza man, all one has to do is say it is so nice of you to think of me, but my parents want me to date Jewish guys, or my parents pick out my dates, etc.