Should world heritage sites be used for commercial activities like fashion and entertainment shows?

It depends on the attribute of the world heritage, let's take a example: the Great Wall of China & the Ming Tombs in Beijing. If some fashion and entertainment activities are held on the Great Wall, it will add so much luster to the scenic spot. However, if the above-mentioned activities are held in the Ming Tomb, it's obvious not appropriate.

So I'd say as a rule if the activity does not harm the site and is appropriate to its nature or function, and does not become the end in itself, there is no problem.