Now, I haven't been an admin on Classic but I was on Delteria and I am pretty sure most of the procedures for banning and warnings work in a similar manner.

We always had evidence to justify banning a player, and because Delteria was a PC server we mainly had to deal with people who would hack/cheat. We always had evidence that they did what they did, even for things like harassment and inappropriate behavior what they said/did was logged and accessible.

If you get banned for hacking and you truly did not do it and there was a lack of evidence to prove it then it gets overturned, which has happened before on almost every server. The only other scenario here is that there is evidence to prove it so it is not getting overturned, if this is the case you don't need evidence because you know what you did.