This post highlights the issues involved when choosing translators.
Last year I needed to have some marketing materials translated into French and Spanish. I mentioned this to two friends (a native French-speaker and a native Spanish-speaker) whom I had met on a translation course. They offered to translate the materials if I translated marketing materials into English for them and I agreed. However, as soon as I received the translated texts I noticed grammar and terminology problems. When I showed the texts to French and Spanish colleagues they confirmed my fears. I had poor quality translations which would do nothing for my professional reputation. After asking for recommendations, I contacted a colleague who was able to arrange for the materials to be re-translated to a professional standard. I later discovered that while both of my friends had taken a translation course, neither of them were working as translators.
This experience illustrates what any professional translator will tell you:
If I had considered these points when choosing translators to work on my marketing materials, I would have saved myself a lot of time and energy.