Savoir-vivre – good manners
Lapses of manners are usually caused by thoughtlessness, rather then maliciousness. Whether its eating too loudly, not saying thank you, or asking a question that would not embarrass you but does very much embarrass the other person, it’s normally caused due to simply not thinking of others, not due to deliberately trying to hurt them. This is something that can due to a lack of education to some extent.
Just being malicious, however, is thinking of others and then going out of your way to hurt them. It can be very thoughtful. From an outsiders perceptive, the most interesting type of malicious behavior is where the enactor is outwardly polite and yet still manages to be hurtful. The victim ends up with their feelings hurt but with no idea how it was done. I think the most common way to go about doing this would be by just changing the rules of engagement half way. First you follow the rules of good manners that you would keep with a close friend and then suddenly you follow the rules you would keep between acquaintances.
You’re polite and thoughtful and appropriate for both occasions, but it’s the sudden switching that wrong foots the victim. If you are confident enough in yourselves, you can reset the terms of engagements whenever you feel like it. The other person is just always a few beats behind, completely gauche, still trying to interact based on the terms of engagement they thought the both of you were operating under.
I guess it’s like trying to dance with someone who keeps changing the dance. Their form is completely correct, but you end up looking like an idiot still trying to do the waltz when they’ve moved on to jitter-bug. (I look like an idiot either way)