Which foods do you cut mold off of, and which do you throw out?

[dienk]

I thought about this again while making dinner this evening. I peeled some onions and found mold under the outer skin. I think it would be very wasteful to throw them out, because a layer or two later, there is no mold.
But regarding other foods, i've seen recent posts here where some people say any mold is disgusting, and I think that's also wasteful.
I cut mold off of fruits, vegetables, hard and semi-hard cheese, and bread. But if I find mold in yogurt, cream, sour cream, or soft cheeses, I throw them out.
What do you do?