Consumers and salespeople lie to each other all the time.
Traditionally the consumer and the salesperson have a classic love/hate relationship. Struggle, tug, prod, and play games - then in an instant, someone wins. The consumer feels he negotiated down to the "best deal ever" while the salesperson tells his buddies about this guy who was nailed by "the oldest pitch". It all happened on the same transaction. Next time, maybe the consumer will return for another fight. Maybe not. Even though he was comfortable with the outcome, the consumer experienced a lot of conflict, tension, and stress over the deal. Those will come back to haunt him when he goes shopping next time.
The consumer hides his intentions. The consumer feels the salesperson has no interest or place knowing his life, his goals, or his interests.
The salesperson hides his profitability. The salesperson believes the consumer will hold the profit against him.
What if both sides were open with each other? What if the consumer said, "This is what I am trying to accomplish and here are the criteria. Here is what I would really like and this is why. By the way, my wife would kill me if I spent more than...." What if the salesperson said, "How much time do you have to spend with me? Why do you want this? Does anyone else have a say in this? Will your wife kill you if you spend more than....?"
Consumers and salespeople both want to make friends. A friend will give you a good deal and a friend will trust your suggestions. Alas, since most people on both sides of the capitalist equation lie to each other, those friendships rarely develop.
Be sincere, be honest, and be genuinely curious. Whether you are a consumer or salesperson, be the first one to start the friendship. You can always walk away should you become uncomfortable with the relationship. When you hit your stride and that first person opens up because of your sincerity, you will know it by the truly satisfied smiles on both of your faces.