To me bad admins are admins that clearly lack the knowledge of the server rules and punish you over supposed rulebreaks that you never committed and/or declare your RP as unrealistic when that RP can happen in real life.
Bad admins are those that are biased towards their faction, friends, legal RP and/or Illegal RP. They then use their bias to punish the innocent party when it's clear the people who they're biased towards are the ones in the wrong.
Bad admins are admins that immediately jump to conclusions and admin jail or ban you because they heard only one side of the story and got influenced enough by the opposing party's words that they're quick to assume you're in the wrong and needs to be punished.
Bad admins are those that let their OOC feelings clout their judgement towards an certain type of RP and say it needs to be abolished/banned because they don't like it.
Bad admins are also admins that refuse to admit that sometimes their judgement can be wrong.
That's all I have to say.