I think you are taking my words a little too literally. For example, I certainly can't get 100% to grips with a new car in a 30 minute or 1 hour test drive but I do get a feel for whether I will like it.
This is what I am saying about getting to try it first - you can touch and feel the stuff and generally get face to face advice - not learn how to use it to perfection though! As soon as I held the 350D and 20D I knew I wanted the 20D (although I was intending to buy the 350D), same with the 100-400 and 400/5.6, as soon as I held them I knew which I wanted.
So, when did I say getting advice and reading reviews on the internet was a bad thing? My remark about bar-codes is that trying to pick between 2 equally good lenses based on sharpness is only going to give you a headache! It will often come down to handling - which you can't test on the internet...
For what its worth, I have bought all of my camera gear in the past 2 years online but always managed to try the major purchases before hand, mainly with friends and acquaintance's kit rather than shops...however, I am now several thousand miles from most friends and family so that will prove difficult in future...luckily one of the Hunts stores is only an hour or so away