No offense, but this is a slow pitch softball.
I can't think of a positive connotation of the word, "ghetto." Unless I am missing some alternate definition. Gingrich posits that Spanish (ergo, their speakers, their culture, their identity) is equated with the "ghetto" --- not a positive association. (Hence you had Latinos angry at him.)
How is Spanish anymore "ghetto" than English? Than Russian? Urdu? Romanian?
Though not an intentional sleight, Gingrich, a public figure, should know better. It's all about choosing your words carefully. Why didn't he just say this to begin with:
"it is important to speak the English language well in order to advance and have success," he said.
....instead of using "ghetto".
He gets the point he was trying to make across, and there's no disrespect towards Spanish speakers. WIN-WIN.
It's funny. The explanations afterwards are always respectful and well-crafted. It would be a whole lot easier for politicians, media types, etc. if they just say the respectful, well-crafted FIRST and leave the stereotypes and disrespect at the door.