The End Result
Visually, the carpet did not look bad, at least from a distance. Close up, you could easily see that the fibers were compressed. When I pressed on the surface with my hand, it felt rough and left an impression that did not quickly disappear. The effect of stepping on the carpet with a bare foot was less than pleasant. In sum, this is not a flooring product that I would want in my home.
I can think of at least one situation in which I might consider painting wall-to-wall carpeting, though, and it might have worked just fine in the studio apartment featured in this Trading Spaces episode. Faced with an ugly piece of glued-down carpet that would be a major hassle to remove, you might decide to cover it with a large rug. You might find, however, that you cannot find a rug to cover the entire floor, and so you would be left with a border of that same old, ugly carpet. Here, you just might conclude that painting the edges of the carpet could significantly improve the overall appearance of the room. I would want to restrict the painting to areas of carpet that would not be walked on, and I would also want to give it plenty of time to dry before I laid the new rug down.
Before taking this step, though, I suggest that you try the same experiment I conducted to see how — or if — you like the effect. I am inclined to believe that dark paint would produce more acceptable results.