In response to the staring/eye contact anon. I’m from the UK and I think we might have slightly different rules for politeness, so this may not all apply to the US. But I think staring is sometimes considered rude purely because it implies a desire to get a lot of information about someone. For example, it might mean:
- You find someone sexually attractive and want to get a good look at their appearance. Most of the time it’s considered impolite to tell someone (even implicitly through staring) that you find them sexually attractive, except in specific situations (for example, I think it’s more acceptable at night clubs and similar places). If you are male-presenting and looking at a female-presenting person, this may make them feel especially threatened.
- You are afraid of someone, or don’t trust them. If you are watching someone do something but not in conversation with them, it might seem like you want to make sure they don’t do something you don’t want them to. For example, if they are in your house, it might seem like you are expecting them to steal or break something. This would be considered impolite because it (seemingly) involves making an assumption and judging someone negatively based on it.
- You think someone is strange-looking. This applies especially in the case of visible disabilities such as wheelchair use, missing limbs, etc. Staring at people might make it seem like you are surprised or even disgusted by the way they look, which can be upsetting. But this same rule applies to people who aren’t visibly disabled. Being stared at may make someone feel insecure about their appearance. For example, they might think “Is there something on my back?” or even “Am I so ugly it makes people stare at me?”. Which can be upsetting.
- There are probably other examples, but these are the ones I thought of first.
Those rules tend to apply the most when staring at someone who you are not in conversation with, particularly a stranger in a public place. But they also apply in a slightly less strong way during conversation and social settings.