Technical people who look down on sales and marketing generally do not realize that just as in coding circles the FizzBuzz test shows a remarkable lack of coding ability in a large population of self-described "programmers", in sales and marketing circles the vast majority of people who self-describe as salesperson or marketer don't have the faintest idea of those respective activities.
To a first approximation, most programmers are barely FizzBuzz material, most sales people are order takers, and most marketers are brand buzzers.
Speaking as a programmer who learned enough sales and marketing to carve out a comfortable niche out in the market, there is a palpable difference between an order taker and a real salesman. It is comparable to say, watching Notch work and watching someone who can't cut FizzBuzz try to implement a stack data structure. I've learned enough sales and marketing to identify the salesmen "rock stars", or even the non-order takers.
A real salesman will hold complex deal variables and details in his head on the same order of complexity as most good programmers will handle in code. He is amazingly good at reading body language and over-the-phone voices, getting at the real concerns of sales objections put up by the customers in an startlingly short amount of time. He'll juggle all these inputs and transmogrify them into a combination that works for the sale, all on the fly in fractions of a second, without it breaking his composure or his speaking delivery. He doesn't look down on the technical people backing him, and instead pumps them for technical information, extracting what he needs to build the business case and relaying it back to the technical staff to make sure he got it right. If you follow him through the day, you'll notice he fills every moment with sales activity; whether he's cold calling or following up, he always has a list of customers to contact and touch in the minutes he has downtime at various points throughout the day, or he's reading up to prep for upcoming deals he anticipates. His day is typically highly structured, and he plans out his activities weeks and months in advance.
There are damn few of these salesmen, just as there are damn few Carmacks. Most of them are tied up pitching large, multi-million and up deals as this kind of talent and work ethic is immediately recognized in sales organizations and promoted or poached away, so I would posit that most programmers have never met such salespeople. When many programmers do meet them, they typically only see the "coal face" side of these sales people, the gladhanding tip-of-the-iceberg part. In much the same way that when a lot of people watch programmers at work, they seem to be "just" sitting and poking at a keyboard now and then.