Last week, the New York Times profiled a New York high school student whose hobby was to learn a large number of different languages. The student, Timothy Doner, now creates You Tube videos of himself speaking in various languages, making him a minor Internet celebrity. By his own admission, he is not striving for near-native fluency in any of these languages, but rather attempts to learn the basics of as many languages as possible.
Doner is part of a select group of individuals who know dozens or more, often very dissimilar, languages, so-called "hyperpolyglots". They collect linguistic knowledge the way others collect porcelain figurines or autographed baseballs. It certainly takes quite a talent to learn foreign languages that quickly and it also helps to start that hobby young.
I'm not sure whether the e-mails I have seen advertising translation services from and into a dozen or more languages provided by a single person were from such hyperpolyglots or from unscrupulous translators. I could see people with a relatively basic (but not rudimentary) command of a language attempting to translate simple general texts, such as an invitation to an event, from that language.
Most documents handled by professional translators, however, are much more complex and/or specialized. So even if the person advertising such services were a talented linguist who collects languages, I doubt he or she would be able to accurately translate, say, a technical whitepaper for a new type of construction machinery into half a dozen languages.
As always, the challenge is to explain to end clients why they are unlikely to receive a translation of acceptable quality from such a super-multilingual translator and why that matters.