Irrational buying

I'm in the midst of reading Predictably Irrational: The Hidden Forces That Shape Our Decisions by Dan Ariely. One of the things I like about it is that his opinions grew out of his own research (I've a preference for analytical and objective information).

He points out several ways that make other-than-rational decisions, for instance, we tend to value more highly the things that cost more. He doesn't say this is a "bad thing" as long as we're aware of what we are doing.

As a store owner, I frequently hear "I'll know it when I see it" or "It has to jump out at me". This is, of course, incredibly difficult for me because it means there's nothing I can do to help, no way that I can assist the customer. I'm not *just* trying to sell something, I want people to pick something that they'll be happy with for a long time. When people buy on a whim, I can't help with that decision making process. Of course, I'm also grateful that folks came to look in Furniture Works, that they think they'll find something here that will "jump out at them".

I, myself, rarely go shopping unless I've done my research and have a pretty good idea of what I want. Am I wrong? Can you tell by looking whether it is the right piece of furniture for you? Or are you better off accessing your needs and choosing the piece that you think will satisfy them? What do you think?