Criticizing,
belittling, or otherwise
slandering any of the line of
Macintosh computers manufactured by
Apple Computer.
Mac-bashing usually is mean-spirited in intent, and is designed to make fanatical Mac users feel insulted, or perhaps make them question their beliefs.
Ultimately, though, I suspect it's counter-productive, in that you're not going to change anyone's mind by Mac-bashing. You'll make the Mac haters feel smug, the Mac lovers mad, and that's about it.
However, constructive criticism or analysis of the Macintosh design or philosophy, or the design of MacOS is reasonable as long as it's done in a fair manner.