Being a world wide company, I get to deal with people from all over the world (logically stunning opening sentance, I know). Thus, we deal with many cultures within, essentially, most conference calls. There ARE cultural differences across the world. Stuff is done differently everywhere. How you talk, what you say, how you close the deal. ALL changes across the world.
However. Much doesn't change.
People buy stuff from people they like/respect/trust. There are versions of this, but at the end of the day people are pretty loyal to GOOD sales people. Good can be defined as "good" or as being "powerful" if that is the way your country swings, but I think it fair to say that good sales people, in ANY country, can overcome product loyalty from the customers.
This came up recently in a discussion with the german application scientist. He was saying, as he gave a very boring practice talk to a group of us that wanted to die, that in Germany people wanted all the data and they didn't care how long it took. Further, germans only bought based on data, not on emotion. He, and I want to state this quickly before I get yelled at, is german. born, raised, educated, and scientifically trained in Germany. He was WRONG. I have sold in Germany. Very well in fact. I was selling with a French guy. We were an excellent team, but we certainly weren't german and we weren't dumping data on their heads. I was, in addition, not making jokes and was a lot better dressed than I was when visiting academic labs, but we weren't boring the pants off of them.
You make the changes you have to make to fit the cultural role of a sales person, but you still have to 'entertain' the audience, and you still have to connect with the customer. Without the connection, they will NOT buy. Even if they are German.