The accent thing makes so much difference. I worked for Ericsson (switching equipment side) for 11 years, and as they had employees from all over the world, being able to understand those accents was one of the skills I developed while there. When I initially interviewed for the job, one of the managers I interviewed with was from Mexico and was very soft-spoken. I barely understood anything he said; I just nodded a lot. I'm amazed I got the job.

The longer I was there though, the easier it got. One of the funniest times was when I was on a customer site with some coworkers from Korea and they had to call one of the top tech support people, who was from China. They couldn't understand each other at all, so I had to get on the phone and translate.
Even after all of that, when I worked in the New York area I still had the hardest time trying to understand some of the locals' really thick accents when I would go out and try to order lunch.