If someone is banned, their profile will look the same as someone whose account is not banned on the forum. I believe that BPIP uses the modlog to account for when an account is banned, and if they show up in the modlog as being banned, they will apply an "autoban" indicator on their website.

I am not sure how bitcointalk's custom implementation of SMF 1.1.19 handles if a particular ban will show up in the modlog or not. I believe at one point, this was determined by the specific procedure a mod followed to ban an account.