In a capitalist society that claims the "customer is always right," it takes pretty extreme incidents for a cusomer to be banned from coming back—ever. But it does happen! Someone asked Reddit: "where have you received a lifetime ban from? What did you do? Have you ever tried re-entering said place? Did you get caught?"
1.) From SPOOFE:
My brother has a lifetime ban from Kickstarter for trying to start a Kickstarter to raise funds to buy Kickstarter.
2.) From Hunting_Gnomes:
I am banned for life from the Mall of America for throwing bouncy balls off of the 4th floor. I wasn't trying to hit anyone, I just wanted to see how high they would bounce.
I go to the mall every couple months like a bad ass. I've never been caught.