So what happens when one goes to buy a car? Or a Refrigerator? Or a Washing Machine? Etc.? Besides the consumer doing his/her own research, isn't the salesperson supposed to be knowledgeable about the product so that he/she can not only just provide information about the product but also probe the consumer to determine which product(s) best suit the consumer's needs?
I do as much research as I can before I make a significant purchase. Regardless, when I walk into a store and I see different models of the product of which I am either not fully aware and/or still need additional information, I ask the salesperson to explain the differences/advantages/disadvantages/etc. between the models. We all know that not all salespeople are well-informed/trained and/or they may have financial incentives to push one product over the next, but in the end, if you need more information than what the manufacturer's marketing and/or your own research can provide, then you have to rely on the salesperson (if you're in the store and ready to buy).
Hypothetical case: Suppose that Best Buy sold me the Surface with RT and I got home and tried to install my Windows x86 apps, I'd take it back and say, "Hey, this thing won't let me install <app>! What's the deal?!" At that point when I'm told I need the Pro version and need to shell out more cash, then I'll either find that acceptable and get it, or not, and demand a refund. It's that simple.
If I am capable and have the resources and skill set to do my own research--but did not--then shame on me for buying the wrong product; on the other hand, if for whatever reason I am completely dependent on the salesperson to guide me, then I'd be fuming at the store and shame on them for having such an incompetent or misguided salesperson. In either case, there's no blame to be put on the vendor's marketing.