It takes two to tango. I don't think I'm rude if I leave you to dance by yourself. Subtle difference between unfriendly (act of omission) and rude (commission of something more).

I do think passing without warning on a MUP errs into the commission of rudeness zone. I'm big on warning before passing as well as the "are you OK?" check if someone seems impaired. If you're just stopped and happy looking, or tootling along OK, I may or may not ignore you and/or your acknowledgment of me. I'm just not that bubbly on an ongoing basis, but I am seldom (though not never) rude.

Travelmama brings up an interesting point (a page back). I bet a lot of people are more responsive to her than to me. Does that mean they're being less rude, or perhaps more rude? I often think the ladies deserve the privilege of being ignored.