After seeing the crap hanging on the walls at my company I believe I could pull stuff out of a dumpster, wrap an expensive frame around it and sell it for thousands.
You could, but you'd have to make it look like unique dumpster stuff, and you'd have to learn to talk a good line about what it all means.
Not until you're part of the right crowd, you can't. Once you've made the right friends, been to the right parties, and sucked up to the right critics, then your dumpster crap will be 'recognized' as art by the arbiters of taste - until then, however, your trash from the alley is nothing more than trash from the alley.