Anyone who uses google translator or any other available translator to translate a thread verbatim ought to be banned according to the forum rules. The act of using a translator to re-write a quality thread that consumed knowledge and time to produce is fraudulent. If it is done with the intention of obtaining a fraudulent merit, I think the user deserves a tag from you (it could be a neutral tag). That is the best way to prevent abuse and maintain quality. If using a translator is what is needed, it wouldn't be a problem for you to use the translator to write your thread in different languages without the involvement of anyone.

There are probably more reasons, but laziness and greed summarize it well. Once a user has the mindset of cheating, they automatically become mentally lazy to do things the right way.