That's an interesting discussion where I would like to add my two cents.... especially on painting a teenager's room...
I have seen parents having tough times while convincing their teenagers for decorating their rooms. Now teenagers would feel that they are old enough to want to decorate or paint their room, but at the same time all the ideas they have are rather wacky. They may ask to paint the whole room with black color and the parents would want to use bright colors

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If that is the situation you are in then parents can usually take a middle way out by letting their teenager to color one wall with black or a color of their choice (usually dark) and other walls can be painted with bright colors.
Hopefully this works!

Matt Walters