Yes, a lot of people will "shop" at a brick and mortar store, then buy elseware or online. I think this is fine if you go in with the intent that if you find what you are looking for, you will buy the product that the salesman is showing you. If you go in fully knowing that you won't buy it, then what you are doing is using up the salesman's time by implying that you might buy. If you told the salesman up front that you have no intention of buying from him, then it is likely he would move on to other customers. There are plenty of other sources of information from the manufacturer's web site, review sites and online forums. There is no real need to take up a salesman's time.

While "shopping" is done by a lot of people, I don't think it is very fair to the sales person. It is about respecting the other person's time and effort.