Downsampled images don't demonstrate sharpness

It seems like every other thread I read here, someone is either complaining about softness or touting sharpness and "showing it" with images that have been reduced in size.

Have you ever taken a tack sharp image, blurred it a few times in Photoshop, then reduced it down, applied USM and then offered it here as showing how sharp a lens is? Well, you can. An image like this will look sharp. It is just simple math= the degree of blur is beneath the threshold of the pixel widths in the reduced image.

When I look at the full-res images made by the pros for my company's annual reports, there is often subject motion blur or even softness because focus wasn't right-on. Guess what? Even with a 120 line screen, the images are reduced down enough that they appear perfectly sharp.

I just wish we could have a "most common mistakes when posting" page.