I've always had excellent to outstanding experiences with Apple call centers. I usually ask where they are near the end of the call, just to be friendly, and they've been in various U.S. and Canadian locations. I've found the agents to be very knowledgeable and genuinely interested in helping. They seem to have access to the information and resources to help.
However, I had a couple calls that were almost surreal. It was like being in a joke about Rogerian therapy, where the counselor just mindlessly echoes back whatever you say. The agents had no interest in helping me, seemed totally incapable of understanding the situation or my request, and either didn't have the usual case information transferred with the call or forced me to repeat everything just for kicks. These calls were frustrating, unpleasant experiences. This had nothing to do with accent and everything to do with interest and ability. Yes, these calls to Hell were routed to India.
I know India has a great number of talented, smart, helpful people. A large portion of the engineers I work with are from India, and my company has engineering facilities in India. But the employees of the Apple call center there are obviously not the best. I've read that in India working in a call center is considered slumming, and working for an American company or answering calls from America is even worse. So, people who can do so get hired at higher status places. If true, this would explain a lot. It doesn't answer why Apple would send calls there, however.