I think that it depends because most bans seems to have a reason for it and to prove otherwise is a daunting task for the banned user. I have read some appeals from here and there and most of the users are ruthless against these appeals especially if they deem it heinous in forum standards.
Every permaban on this forum was justified, except in rare cases of selling an account to another user.
Therefore, complaint in which the user claims that he is not guilty and that some error has occurred has no chance on this forum.
The only thing that can help is a full guilty plea, an apology, the member needs to prove that his contribution to the forum is such that he deserves a second chance, and most importantly, the support of the forum community is very important.