I agree that many people think they speak a language when in fact they do not. I have heard people saying "I speak a little whatever" but they cannot say more than "hi" and "goodbye", literally. In this case, it does not help.
That said, "the 2 years of French" help tremendously. Few people travel and start discussing very complicated topics, and other than the phrases mentioned before on this thread the 2 years of French do allow someone who is relatively interested in languages to have a nice conversation. Also, it helps tremendously in reading maps, signs, listening to an announcement, etc.
I do not see how knowing a language, even the 2 year course, cannot be an advantage to anyone.
About speaking Spanish/Portuguese as mentioned before, or any languages that belong to the same group... I think first and foremost, traveling to a country without even knowing what language is spoken there is simply unthinkable. At least learn a few facts (language spoken, the very least you should know, hello?!) before you go, be a pleasant traveler, for Heaven's sake.
I have never traveled without learning a few phrases and I
always buy a quick dictionary (small booklets with key words/phrases). No matter how busy I am, I have many hours in the plane to study that very well. And people are appreciative you are trying to speak their language, they genuinely are.
I think it is a case-by-case thing. People get insulted when you speak another language
supposing that is their language, but if you
clearly say something like "I am sorry, I know this is not your language, but this is the closest knowledge to your language I have and you don't speak mine" I am sure 99% of locals will be nice to you.
All in all, it really depends on the traveler's attitude.