We all look like idiots when it comes to pronouncing names. One way you can tell whether someone is a native of the area is how they pronounce "Puyallup". Sometimes, the same spelling has multiple pronunciations depending on the referent, for example Lima Ohio (lɑjmə) and Lima Peru (lijmə). There can also be relatively free variation in pronunciation, for example Yakima can be [ˈjækəmɑ:] or [ˈjækəmə] though I think the former is prevalent amongst locals -- [jəˈkajmə] is clearly wrong, although possible. Personal names pose the same problem, to the point that "Levine" can be pronounced [ləvˈijn] or [ləvˈajn], depending on which person you're talking about. The name "Nguyen" is pronounced a lot of different ways; usually not the way it is pronounced in Vietnamese, but some brave souls persist. You can make some guesses, e.g. that an Asian with the name "Ngo" pronounces it [ŋo] and an African with the same spelling pronounces it [ŋgo], but it might also be pronounced [ŋo]. Guessing nationality is even harder (is "Lee" Korean, Chinese, Malaysian? Or even not Asian?), or impossible if you mean "what is their citizenship?".
Which is why I always ask the speaker, when introducing a person I don't know, how to pronounce their name.