You've gotten through the interview and now the sales recruiter or client asks you "do you have any questions?"
What has the performance of the territory or team been over the past year or 3 years?
You want to know so that there are no surprises. Of course wait for the answer before asking why.
How much turnover is there at this company or in this team?
A high turnover rate is an indication that there may be some serious problems. You might want to think about joining the team or company.
What's your management style or what's the culture of the company?
It's all about fit so take the time to understand if you fit with your potential manager and company.
Why is this position open?
Is it a new job, a firing or resignation?
Again, compare the answers you get here with the answers you get about turnover. What you are looking for are indications that the company takes its time to hire, support and evaluate their people. Too quick of a hire or too quick of a fire may not be the environment that you are looking for.
How do you compare to your competitors?
You should have done some research before the interview and have an idea of their competitors. What you are looking for is their competitive advantage. This is the cornerstone of every sales person's job. Knowing their strategic advantage will help you sell. This will also tell you if you are in over your head. If you are a transactional rep that sells on price and you are interviewing for a value-added sale, perhaps the jump will be too high or perhaps it's exactly what you're looking for.
Where is the industry going?
This will tell you things about growth, their role within the industry and growth potentials for you.
There are many other questions that a sales candidate can ask that may be pertinent. The key here is not to dominate the interview. Look for signs that the interviewer is bored or pressed for time. Be sensitive to the time allotted. Many candidates miss this part.
One of the most important part of asking questions, is to come prepared with a pad and paper and write your answers. Many candidates miss this part. Some clients look at this lack of preparedness and an indication of the type of rep that you will be.