Where on earth did you hear this? No! Very untrue! Dirty skin does not equal bad skin.

If you wash your face too often your body will create more sebum to compensate, leading to further breakouts. Washing your skin takes away all the sebum on the surface. Your skin actually needs a small amount of sebum on the surface as this is your skin's natural lubricant. So naturally, if your body detects that your skin surface is lacking in sebum it will create more. More sebum on the surface means more blackheads (as blackheads are not dirt, but dry sebum) and more acne. Washing your skin too often will also irritate it more.

Twice a day. That's all you should need. If you find your skin really oily in the middle of the day I suggest... face paper! Sounds weird but it's actually really awesome. It's basically blotting paper that will draw away excess sebum from the surface of your skin during the day. I use it when I start to feel a bit greasy-faced or when my skin looks shiny. I can give you more info if you want to try it. Very cheap.