We can use all sorts of tricks to catch plagiarists and they'll just make their posts more and more obscure - copying from outside sources, translating from other languages, etc - as long as there is a financial incentive to do so.
The lengths some people will go to in order to avoid having an original thought are pretty amazing. I mean, how hard is it to just think of a sentence in your head and transcribe it into a post?
The other day a WO semi-regular was banned for copying sports articles written in Italian and Google Translating them. He was a legendary too. Possibly the worst part is he's not even Italian.