When you feel you are being sold you question the intent of the other person and do not feel that you are in control of what is happening. Just the opposite is happening when you know you are doing the buying. It is fun. You enjoy it. That happens when the sales person is clearly on your side and does not stray from what you want.
Referrals help immensely.
Point to other evidence of successes. We do that with our ability to ask relevant questions and use intense listening. Know your customer. Point out the difference, so they can recognize their problem and discover the feelings they want. You can not present a solution to a problem that someone didn't feel he had.