I have great sympathy for people working in retail computer stores, but really, there's no reason to just make things up.
If you invent an answer just to get rid of an irritating customer, there's an excellent chance he or she will be back within hours, more upset than ever. If you're lucky, s/he will corner some other unlucky employee and vent, but if all the employees do that, there's nowhere to hide.
I try to avoid my local CompUSA, but I can't always; they're the only 'certified Apple retailer' in the area. Never have I been in there when every single employee wasn't busy answering questions - vast numbers of questions, many arising from a misunderstanding of the technology that is so fundamental that a brief answer is impossible. Unfortunately (even tragically) most people go into computer stores as much for information and education as to buy merchandise, and retailers do their customers a disservice by not training their employees better.
On the other hand, this phenomenon DOES cost those places money. For instance: often when I go in there, I know exactly what I want, but it's locked in a glass cabinet, so I have to wait until one of the employees can slip away from the clueless horde and grab the key. More than once I've walked out empty handed, even when the desired merchandise was clearly visible in a cabinet, because I just ran out of time...
Maybe I should carry a sign: "I have no questions, know exactly what I want = easy, instant commission". ;-)