I have autism, so it really doesn't matter how good your joke is, I will misunderstand it in fresh and novel ways.
/s is letting the audience know that it's a joke. If you think that makes things unfunny, then comedy clubs must be awful for you. "Why is everyone laughing, it's obvious he's telling a joke, that ruins the whole joke. Don't they know that ruins jokes? Jokes need to be secretive games where only clever people like me know they're funny in order for it to be funny!"