It's ironic that given how common simple (not contributed to by anything other than stopping) falls are with clipless pedals that a bike shop might be more inclined to let some random guy walk in with clipless pedals/shoes and go ride a bike that needs to be kept pristine.

Just in case another newb asks a similar question, let's get answers to the following questions: Should the shoes and pedals be well-worn to indicate prior usage? Should the prospective buyer bring along a sales receipt to prove that they are his pedals too? Perhaps should a picture showing him riding a bicycle with those shoes and pedals accompany the sales receipt?