That is a good way of looking at commission based sales jobs, but in my experience it also can depend on how the company implements their commission policies.

When I was in college, I worked at a Fry's Electronics in the computer department. I liked the job as it worked around my schedule, but at the time, the company was trying out a commission only based pay for floor salesmen in both the computer and electronics department (salesmen in those two departments did not get a base pay and only made money of commissions). It did mean that as a salesmen you did have to work harder for your money, and you had the opportunity of making a lot of money in sales, but it also pushed the salesmen to sell things to customers that they might not have needed.

For example, Fry's would have cheap computers that they would sell basically at cost to get people in the door. These computers, since they were at cost did not generate a commission if the salesmen sold one. This meant that some salesmen, seeing these as a waste of time on their part, would direct customers to the more expensive machines to get a better commission (even if the customer just wanted a cheap computer). The store also pushed Monster brand products (HDMI cables, etc) that had a high markup for the store (and also a much higher commission to the customers). I hated pushing these things because most of the time the customer could get the same quality cable from a less noted brand at half the cost.

I do agree that commission based sales will push the salesmen to work harder, but there has to be a compromise that benefits the salesmen in compensation and benefiting the customer in getting sold the products that are best for them.