It might help if we agreed on a definition of "greed" here, or at least take note of which one others are using. I usually use the textbook definition:
excessive or rapacious desire, especially for wealth or possessions.
Emphasis on
excessive. As in, if your desire for wealth is so strong that you've just sold your grandma into slavery for thirty pence, yeah, that's definitely excessive, and it's definitely bad.
I understand the desire to defend it as OK when people start saying ridiculous stuff like "You don't want to pay taxes?! You're just an evil, greedy ogre!" But:
(1) That's hardly greed. Wanting to keep what you earn is in no way "excessive."
(2) What it IS, is simple
self-interest, which is what most free market supporters accept as OK, and really, one can't argue that.
Calling greed good may be an effective way at making liberals/socialists/etc. flinch, but it hardly seems to be defensible without conflating greed with self-interest.