In my family, it has been always cultivated that being a salesperson is a kind of a wicked thing and a dead end. Especially if you are an Engineer. Looking back to this attitude now I realize how wrong it was. Sales is a crucial skill to survive. Because the first thing that you must know how to sell is yourself. It is your experience, knowledge, portfolio, contacts, talents and etc. I assume, that sitting at the negotiations table with your potential employer you think really hard about, how to get as much as you can from him (and do as little as possible (joke)).