I'd just have to write a side-script to prevent users from just wrapping their messages in ["quote"] tags.
Quoted text isn't counted for payment for signature spammers, so they're unlikely to hide their plagiarism that way.
Never knew that. But I cant see why some one would copy-paste. Good to know its checked. At first glance BTT looks complicated for me. But I now understand the complicated for a lot of reasons.