These are a group of questions that we have found that work well in understanding and qualifying a salesperson.

1. Tell me about your last three days at work -- beginning to end.
2. How many first appointments do you have each week?  
3. What do you like and dislike about the sales process and why?
4. What do you like and dislike about the products or services you're selling now and why?
5. What attracts you to the <your industry> industry?
6. What are your long term professional goals?  
7. What do you do personally for your professional development?
8. What are your favorite selling books?
9. What type of sales cycle is most rewarding to you? A long cycle for a big ticket item or a series of smaller, more frequent sales.
10. As a sales professional, what do you see as your primary and secondary roles within a company?
11. In your current position, how much time would you say you spend directly with prospects and customers throughout the sales day and what specifically do you do with them?
12. Describe a situation with a client or prospect where you made a mistake. How did you handle the error?
13. Describe a couple of instances, big or small, where you took a different tack in achieving an objective than was the company standard?
14. Describe a time where a creative approach to meeting an objective didn't work and what you did next? 
15. What do you think are the most important skills in succeeding in sales?
16. What are your top three open-ended questions for initial sales calls?
17. In your current sales environment, describe the process you go through to qualify your prospects?
18. What is the largest group you've presented to (externally/internally)?
19. How do you organize a presentation?
20. What do you like and dislike about presentations and why?
21. What do you see as the key issues in negotiating?
22. What do you see as the key skills in closing?
23. How would your present prospects and customers describe you as their sales representative?
24. What would you say your one or two biggest failures or mistakes were? What did you learn from them?
25. What are some of the challenges you see that are facing this industry?
26. How would those with whom you work now, across all areas of the company, describe you and the work you do?
27. Describe a time your company did not deliver on its product or service and how you responded?
28. Describe one or two of the most difficult challenges and/or rejections you've faced in the past and how you responded?
29. How many rejections do you take in a typical week?
30. How do you move forward from a string of rejections?