I should have emphasized more strongly that I was talking strictly about optical properties in the abstract, not imperfections or bad figure in the glass, poor quality in general, or mechanical shortcomings with the tube assembly or the mounting (an oft-neglected consideration). The best scope is worthless without a proper mounting.

The traditional example for this is the "department store" telescope, usually advertised with a magnification an order of magnitude higher than theoretically possible for even a flawless objective of that size.

Anyone considering getting into astronomy, or considering buying a gift scope for a child interested in astronomy should contact one of the astronomy groupies here in the Zone for advice. There's at least three that I know of, myself, SteveS and RobVG.