I've been to the L.A. consulate for many years (and hopefully, now, I won't need to go back there for the next 9 years ). I've witnessed many times when people were turned away because their application was either incomplete or rejected outright by the clerk at the window. I myself always needed to present a handwritten addendum to my application because of my profession. However, once the application is accepted, it's pretty much a guarantee that the visa has been approved. I've never seen anyone being informed at the pickup window that their visa turned out to be rejected.