Hey! Lookin' Good!!

[Mireille]

it's rude to post a screenshot of other characters with their names without their permissions.

In most countries it's lawfull to photograph a person in a public place without their permission. They may get angry, but they can't prosecute. It is also generally lawful to use such an image for purely artistic purposes without a model release form being signed by them.

People's reaction varies. They may get angry, or they may love the photograph. To me rudeness is a question of is the image respectful or disrespectful in the way it presents them.