The message is only displayed when directly viewing the profile and is not under every message they post.

It remains that plagiarism is very unethical (in addition to being harmful to the forum), and is not unlike stealing when the person believes no one is watching.

I see the message as a warning to anyone who will potentially consider paying for advertising in the future that the person may not be someone who will be the most effective advertiser. I also do not believe this warning to be inappropriate.

I think for the most part, someone who is banned from wearing a signature is probably not going to be posting very much anyway, and mostly were here solely for the signature money.