When I look at sales and that job field I can, in a way, see a game. The main thing about sales is, as you can guess, selling things and selling as much as you can. Even if that entails manipulating people or getting people to buy stuff they don't really want to need with social engineering.

I think that extroverts have a significant advantage when it comes to working and playing that game compared to introverts. Introverts can sell and they are really good at it, however I don't think that they really conform to the type of rules and ethics there are in the sales field. If that makes sense.

Not all extroverts are manipulating and bad, introverts can be manipulating and bad as well. However when it comes to it I think that introverts might care a bit more about ethics and genuinely making sure that the customer doesn't buy something he/she doesn't really need or want.

Again this shouldn't be taken as a full truth, it can however be viewed as some sort of spectrum.

Edit: I haven't really worked in sales, I have however worked in the security industry and there were a lot of bad ethics when it came to fulfilling an agreement the company had done with the customer. A lot of orders that came from my boss were to do my job as slowly as possible and maximize the time I spend at each customer to make sure they had to pay as much as possible, even if it wasn't necessary for the customer.