When two people meet, and one wants to sell, while another wants (thinks of) to buy, the standard rules apply. They imply that no matter a seller says his final goal is clear: to sell. A buyer knows that perfectly, he is usually not so stupid at all; he sees all the tricks, which intended to make him to buy. More than that, he implicitly accepts those.
But what if a seller decides not to just sell, but first to understand unique needs of a buyer? Genuinely. To the point, when he can honestly recommend competitor’s offering, if his own product is not fit enough. Or to spend some of his time helping a buyer to solve his problem, for free, with no second thought of selling.