Personally, I hate wasting a dealer's time.
What frustration? They post it out, you listen, buy, or return. No different to listening instore then deciding at home later that, ah, not for you. But then, you've bought it instore and the dealer doesn't have to take it back. Who's frustrated then?
All you mentioned was something you heard in a shop and the dealer suggested something else. Alternatively, you do a bit of legwork beforehand, read up and do the homework. All my current system, all of it, was bought blind. Works a treat too.