Common use: Covered with a thin layer of gold, a precious metal often used in jewelry.
Slang: Genuine and true, but not in a good way. The mock formality alludes to a professional judgment.
1. Yeah, I know him. He's a gold-plated prick
2. My car just broke down. I swear that thing is a gold-plated piece of shit
3. My boss is ok, but his boss is a gold-plated asshole