Usually, people who are banned for one thing or another, but in this case, plagiarism always gets red-tagged and it's usually not just one, especially for a user who does it often, so after two years they still won't be able to join any signature campaign because most campaign managers don't add people with red trust to their campaigns. Am I wrong?
Who gives red tag for plagiarism? that offense is related to forum moderation policies alone, nobody on DT has the rights to tag people for that, if you see any, you should report it on reputation board. we can't have everyone on DT to make up their own rules on every thing, so I doubt we see such cases.