In terms of purchasing something as important and expensive as a firearm, as far as I'm concerned, the responsibility for making a prudent purchase falls squarely on the shoulders of the buyer. If you're naive enough to stroll into your local car dealer and ask the salesman which is best for you, a convertible or a station wagon or an automatic or a standard transmission and you end up with something that's less than suitable for your own needs, you have only yourself to blame. Likewise, if you have to ask a salesclerk which is best for you, a revolver or a semi-auto pistol, and you end up with an inappropriate choice for your particular circumstance(s), look into the mirror if you think someone needs blamed.
Speaking for myself, whether I'm buying a gun, an automobile or a toaster for that matter, I feel it's incumbent on me to do the necessary independent research on a product before making a purchase decision. Some of that research may well involve quizzing a sales clerk, reading enthusiast's publications, talking with informed friends or acknowledged experts at my local gun club or even consulting some of the people on The Firing Line who over the years I've become comfortable with in terms of their knowledge base and general expertise (and, most likely, my ultimate decision will be predicated on a combination of these sources of information).
And, still speaking for myself here, I really have to question the motives of people who lurk in the dark corners of gun shops in the hopes of overhearing erroneous advice from stupid clerks to unwitting prospective customers, just so that they can enlighten the dumb with their smart counsel. Boorish behavior in the extreme.