Your sales people and product managers have a powerful tool at their disposal: caesuras. A caesura is a pause in prose or melody, but it also is a pause in a conversation.
Sales people have long used the caesura to generate mild discomfort to stimulate concessions during negotiations. People feel compelled to fill lulls in conversation.
A product manager can use this technique as well. When conducting one-on-one interviews, sometimes the best approach is to be quiet and let the prospect say something unsolicited. Not only does the interviewer not know all the answers, she also doesn't know all the right questions.