Great sales representatives -- what makes them great?

Yesterday, in a flash of inspiration, I drafted an email and sent it to a sampling of our database, offering a free $50 gift card for people who could recommend the their 'best' client or supplier salespeople.

So far, several people have responded with specific names, who I expect to call within the next few weeks to gain a better understanding of what makes someone in sales 'great'. I realize there are risks and limitations in this unscientific, reward-based survey. The individual making the recommendations may lack authority and simply want the gift -- and the sales reps referenced may be great at client service for existing customers, but less able to find/discover new business.

Nevertheless, I'm hoping to see if there are common denominators among the organizations which hire these representatives, and their behaviour/connection with clients.

I'll report on my interviews/findings in the weeks ahead.