Whether you are using machine translation to understand someone else, or to get them to understand you, it makes it more likely that the message will be poorly understood, misunderstood, and unprofessionally presented.
Consider what it has done to the following three sentences originally written in Spanish:
Google Translate translation: “About 12 million Mexicans -15% of the workforce in Mexico-legally or illegally residing in the U.S., according to the Pew Hispanic Center.”
First off, where is the verb?! It seems to have vanished.
If these Mexicans are “residing in the U.S.,” how are they also “in Mexico”?
Are they “in Mexico—legally or illegally” or are they “legally or illegally residing in the U.S.”?
Original sentence: “Cerca de 12 millones de mexicanos -15% de la fuerza laboral de México- residen legal o ilegalmente en EU, según el Centro Hispano Pew.”
Real (human) translation (i.e., the true original meaning): “About 12 million Mexicans15% of Mexico’s work forcereside, legally or illegally, in the U.S., according to the Pew Hispanic Center.”
Google Translate: “Remittances sent by Mexicans from the United States has grown from 3.700 million in 1995 to a high of 25,000 million dollars in 2007, according to The Washington Post in 2012.”
Were remittances sent “by Mexicans from the United States” or “from the United States by Mexicans”?
Who says “remittances...has grown”?
Why the inconsistency of “3.700” for “3,700” early in the sentence, followed by “25,000” (and not “25.000”) later on?
How many U.S. readers describe anything in terms of “thousand millions” or even know what “thousand millions” are?
Original sentence: “Las remesas enviadas por los mexicanos desde Estados Unidos han crecido de 3,700 millones de dólares en 1995 a un máximo de 25,000 millones de dólares en el 2007, según informó The Washington Post en el 2012.”
Real, human translation: “Remittances sent from the United States by Mexicans have grown from $3.7 billion in 1995 to a high of $25 billion in 2007, according to reporting by The Washington Post in 2012.”
Google Translate: “The figure of 25,000 million represents about 3% of gross domestic product of Mexico.”
This is less ambiguous and has fewer errors, but it is still not expressed in properly written English. Yes, it is understandable, but this Tarzan English is not the kind you would want representing your company. (Tarzan Spanish doesn’t sound any better.)
Original text: “La cifra de 25,000 millones de dólares representa aproximadamente 3% del Producto Interno Bruto de México.”
Real translation: “The $25 billion figure represents about 3% of Mexico’s GDP.” (That's better.)
Although I would like to think this would dissuade someone from using Google Translate or other machine translation programs, I have learned that this is what happens instead: You see the errors here, you understand how machine translation has mangled this message in ways that mean the user of the translation is not getting the correct message, and that that message is not being delivered in a professional way, and then...next time you want to "know what this says" or "translate this into Spanish," you just go and do it again.
It's like the "pointy-haired boss" phenomenon in Dilbert. The boss goes by your cubicle, sees the Dilbert comic featuring the stupid, pointy-haired boss, maybe even reads it and laughs out loud, but never seems to understand that the joke is really about him (or her)! And that's probably a good thing for you; otherwise, you might get fired. But the point is, even though what I have shown you here applies to the effects of machine translation on this specific message, it also applies to any message and, yes, it also applies to your message.
I know I can't stop you, but I try. It may take some major miscommunication that does some major damage before it really sinks in how important clear, unambiguous, professional communication can bewhether that is for your business or your personal life. Like the case of the business owner whose "Spanish-speaking" employee saw the word "celebrar" in the fax from the major client and thought that meant it was announcing a party, and therefore not anything important, when in fact what was being "held" (one meaning of "celebrar") was a crucial meeting that the business owner should have gone to!
Then again, maybe, just maybe, you are one of those wise people who can learn things the easy way ("A buen entendedor, pocas palabras."), and you will know, from this day forward, that machine translation may give you an idea of what is being said, but it virtually always gives you wrong ideas.
If it is important to communicate correctly, it is important to use a skilled human translator, and not a machine that does not understand what it is reading, and even less what it is saying.