I have noticed that the one Hispanic Congregation here in central PA does very well, and having attended there before, I can attest that they always have strong attendence. I think the Hispanic Congregations focus more on the social aspects of meetings and tend to care less about doctrines, they don't get wrapped up into it as much. Perhaps, they are less willing to question doctrine as long as they are able to get along socially and use the KH more as a meet up place rather than a more religious place.
Of course, it's also fun to go to these meetings especially if you don't know Spanish very well. You just sit there and day dream, you don't even have to answer and then after meeting you get to hang out. Still not worth it, but better than a boring white congregation where everyone is all up in your face.