I have a nice printer: an HP Color Laserjet CP1515n. It printed really clean, strong colours until a few months ago, when it started displacing the magenta. Check out this portion of the Ubuntu GNU/Linux test page:
As you can see, each individual nozzle (cyan, magenta, yellow) produces a really nice, clean print. And the green composite comes out nicely, too, because the cyan and yellow nozzles are correctly aligned. But the red (= magenta + yellow) and blue (= cyan + magenta) are fuzzy, because the magenta nozzle is not correctly aligned with the other two.