If a salesperson can't understand the range of marketing goals an advertiser may be losing sleep over, then she can't begin to offer the solutions that will culminate in the big sale. Great Internet ad salespeople need to understand not only their own offerings, but all the other choices a buyer has available, if they are to make recommendations that actually solve problems. At the same time, there are a number of core skills associated with any selling job, and those skills demand reinforcement and refinement over the course of a career. Lead screening, prospect qualification, proposal design, negotiation and closing skills are all deserving of regular practice and improvement so they don't get rusty. Training programs provide the ability to try on new approaches, without risking the business in front of your buyer.
Internal sources are best at providing information about the product each salesperson is selling.
So, to those training proponents who wrote in, we thank you. Do the Math. Voice your opinion. But many among us have come to think of that quest as quixotic. Positioned between the media and technology suppliers on the one hand and the spenders on the other, an ad agency is like a middleman, aware of the motives and objectives on both sides.