They are like Big Puppy Dogs, and the prospect of you buying a bike is like the prospect of a walk. Browsing round the shop, talking geometry and composite materials is like waving a lead and bouncing a tennis ball.
Before long they're drooling uncontrollably and bounding round, trying to sell you anything, anything - a Trek Madone? this used cruiser? a ladies' cargo recumbent?
When you walk out that door without laying down your MasterCard don't look back, or you'll see the saddest eyes in the universe.
BONUS TIP: Shop guy is no poodle push-over. He is smart like a border collie, and if you try this too often he will poo on your front lawn.