It's always interesting interviewing candidates for sales positions. Given that the interviewee is effectively trying to sell the interviewer, it's important to watch the candidate's technique very carefully. One should pay particular attention to their listening and questioning techniques, of course - it always amazes me when a candidate cannot repeat back to me basic facts I shared about the company 5 minutes earlier.
I also like to take careful note of the attitude towards sales prospects. Candidates who tend to "de-humanize" prospects are a big red flag. The most profitable and rewarding customer-vendor relationships are always the ones with a high level of mutual respect and integrity. A salesperson who sees each person as an individual and treats them accordingly may not necessarily sell more, but will bring in more profitable business.
As the above video illustrates quite effectively, the same can be said of the customer service people at a business software company. Where the technical support department uses a "one size fits all" approach, a significant percentage of customers end up dissatisfied with the responses and solutions provided. Same thing where rules of engagement on implementation and consulting are rigidly applied without first understanding the specific customer's situation.