This is really important. I love programming and am somewhat introverted, but being newlywed with a wife who couldn't work (visa), a mortgage, and a commission plan really made me learn to sell. The really good salespeople aren't deceptive, and I luckily learned from them.
Also: if you're at a good company the engineers don't scorn the sales people (instead: "you guys bring in the money that pays our salaries") and the sales folks actually sell the product to people who will benefit from it.
I've always tried to sit in on a few sales calls at any place I've worked and have encouraged people working for me to do the same. It's valuable to see your products from the Sales team and customer perspective. The surprising thing I've observed is how great sales people spend most of the call listening to problems, not offering solutions.
I always have every member of the exec team attend a sales call per quarter. Yep, even the CFO. Amazing the impact it has on the staff meetings, much less the decisions made.
Also: if you're at a good company the engineers don't scorn the sales people (instead: "you guys bring in the money that pays our salaries") and the sales folks actually sell the product to people who will benefit from it.