I don't think so.
In fact, this is how Germans, even those who have otherwise very good accents, give themselves away when they are speaking English. Many a fluent German speaker of English will betray his or her origins by inadvertently saying 'lap' instead of 'lab', for example.
This doesn't happen with native English speakers. A 'b' at the end of a word is softer, less clearly articulated, and slightly less 'plosive' that when it occurs in initial or central positions, but it is never devoiced.