It looks a bit harsh and cruel to permanently ban an account for spamming, plagiarism, or whatever the (similar) reason is. It's like a lifetime prison!
Before starting a topic like this, you should read or re-read the pinned topic first.
Unofficial list of (official) Bitcointalk.org rules, guidelines, FAQThe rule #33 (last one) is:
33. Posting plagiarized content is not allowed.[e]
And, theymos emphasized that
even years after the publishing day of posts, if plagiarism found, users will get permanent ban.
I will quote the original post of theymos later, when I saw it again, not found ATM. I don't remember where I read it 
Recent weeks, one user raised a request to un-ban for permanent banned users if they improved over time (or something like this, if I remembered well).
Alternatives to Permabans for plagarism (by
hilariousetc)
I have to hangout now, sorry.
