I largely agree with your comments but as maczrool says "A graph of the speakers' response is helpful, but rarely available" and, considering the box-shifting stores I mentioned, that's almost certainly a given IMHO.

Considering the remarks here, I will certainly try to make a more informed buying decision but I can't help feel that, at the budget end of the scale, store tests in less than ideal conditions are, realistically, the best I can expect (but I hope I'm wrong).