As has been mentioned, no matter ** how ** polite they might be at the door, the fact remains, I didn’t invite them to stop by. case closed.
As far as the rest of it: my experience is based on a sample of two.
A secretary where I work was/is a JW. Found out by accident once, she never made it an issue at all, just very matter of fact, “we don’t exchange gifts” kind of thing. Highly respected for that. Plus, she never came to my door unasked.
The second was a b/f who’s family was JW. When we’d go over to his family’s house for a meal, it went like this: We’d knock at the door. If it was his dad or brothers that answered, they’d walk away from the open door with out greeting. If it was his mom, she’d say hi, and welcome us in. See, the dad and brothers were “strict” about not “consorting” with non JW’s. I found that to be rude. but, that’s just me.