You should never use a machine translation system like Google Translate for any type of professional or important document. Machine translators don’t have any linguistic context and consequently, documents that turn out wrong. Even though Google translate has improved with context clarification for some words, but it isn’t perfect just yet.
The other problem with Google translate is it isn’t locale specific. So, if you happen to be translating from English to Spanish, you can’t specify which dialect of Spanish the document should be translated into.
A human translator understands the content of the message, and he or she can make sure that it is not offensive in any way in addition to being adequately translated.