Angie's writing about burgundy, and my own feelings about being off most non neutral colors got me wondering- how do you know you're really "off" something enough to pass it on?

What are your criteria for keeping vs donating, when you haven't worn something for a while?

I used to pass things on without regrets, but lately have thought in some cases, that I should have kept things. I don't want to rebuy when my mood inevitably changes again- but I also don't have extra space and hate clutter.
Thoughts?