If your ass is not making it to the session on time at 2 pm like we agreed on multiple times in a row, I will not trust you to be on time for an event.
If you are making absurd demands of the DM and try to bully them to include your overpowered item (including homebrewing it for you and then you throw a fit when you don't like the results), I will not trust you with real power. etc etc
EDIT: I am not looking for DMing advice here, I already do sessions 0, read articles and have dmed and played a lot. I am mostly noting how small shit can tell you if you can rely on/trust somebody for more serious stuff and that TTGs have a lot of small shit coming together at once.
I fortunately haven't had to set such rules out on paper in quite some time because I have a mature group (mature as in emotionally and socially developed, not media consumption as maturity identifier) and it also helped having more women in it than the "old school hardcore" douchebags would feel comfortable with.
spoiler
Spoiler: The number of women in a group that douchebags tend to feel comfortable with is zero.
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I used to hear them be called "catpiss" because of the stench they brought into hobby stores. I used to think that was unkind, but... it often did apply.
Not always. My very worst player of all time was more a style superficially clean and tidy sort that kind of wanted to be in the game while being praised for how free spirited his "Chaotic Good" cruelty, torture, and enslavement antics were.
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