Native American speakers generally sound awful when speaking German. The problems are manifold, but I think the primary ones are (1) inability to pronounce German "ich, "which appears in hundreds of words. This sound (which one is always told approximates to the "ch" in Scottish "loch) unusually comes out as a "k" or an "sh." (2) Germans has a trilled "r" and a so-called throat "r," which actually does sound rather like clearings one's throat, and it's a rare American who masters either to any degree. (3) German likes its vowels pure; that is, the initial sound of the vowel is preserved from onset to end. Both American and British English have vowel "glide," i.e., a falling off or tapering of the sound at the end of the vowel that alters the overall sound. Americans find pure vowels almost impossible, especially those from the South where one can find just about the most impure vowels possible. By the way, Germans generally find the glide impossible and therefore clip syllables. It's a two way street. I should also note that German still has a plethora of local accents and dialects -- the like of which we seem to be losing her in the States. I learned German as a very young child in Austria, and although I have lived in both Northern and Southern Germany, when I speak German today I still incorporate certain Austrianisms.
Lee