Can someone who has been banned ever come back?
It’s happened a few times, yes.
Why? Are you planning something? 
Maybe she’s curious about those mystical after-banning or near-banning experiences.
It used to happen occasionally back in the early days of the board, back before we formalized the warning system or used suspensions. Some posters asked to be re-admitted after banning and were allowed back in. However, they almost invariably committed the same kinds of offenses as before and were banned again.
Nowadays a poster is usually banned only after multiple warnings and a suspension. It’s unlikely we would allow anyone back in under these circumstances since they have already given plenty of evidence they aren’t going to follow the rules.
We’ve sometimes mistakenly banned people for spamming or socking, and they may be readmitted once we’ve investigated and found the banning wasn’t merited.
And let’s not forget the Great Mass Banning.
Aye… the day that Marley banned us all… and we all came back. In a way, we’re all examples of those who have been banned (however unintentionally) and were allowed back in 
♫ Unban my heart… ♩
No, I’m not planning for a banning. 
Cruising for a bruising?
Wheedling for a warning?
Seeking a suspension?
No, I don’t have an intention to get a suspension.
Then I suppose you are wary of that warning also? 
Do Dopers ever have Near Banning Experiences? You know, where they hear a voice that says “Move toward the Pit”, or they can see their username leaving their body?
Got a good chuckle out of me. Shame on you!
And once in a while someone who was banned years ago will ask for another chance. In a couple of instances we’ve said yes.
Prodding for a modding?
If I may, I think EmilyG would be mortified by a modding, yes?
We will one day wail at the ways of our wandering.
Geez, that’s all we need now, taser prods for mods.
I keep suggesting this, and I keep getting turned down. I have no idea why.