A long time ago, I worked on a big horse ranch where part of my job was showing people colts we had for sale. I didn't much like that part of the job. My boss was a person I could talk to about pretty much anything, so I told him how i felt about this. He suggested that I look at it differently. Because, the way he saw it, we weren't trying to manipulate someone into buying a horse, we were trying help them find the horse they were looking for (hopefully one of the ones we had sale).
I found that perspective to be pretty helpful. After all, most prospective buyers want to buy something. I don't think it's normally my responsibility to convince them otherwise. It's more my responsibility to accurately represent the product and help then decide if it meets their needs. When you venture into the area of trying to protect them from themselves and make their decisions for them, I think we're venturing into areas where we're taking on responsibilities aren't actually ours.