'Million Dollar Listing L.A.' star Madison Hildebrand came THIS close to putting pen to paper for a $300k deal to speak at a conference in Dubai ... but like with Dog the Bounty Hunter, it was a total scam. One of Malibu's most sought after real estate agents tells TMZ ... he got a fake $300k…

"Million Dollar Listing Los Angeles" star Madison Hildebrand had an interesting showing at his own house this week ... a guy walking around naked showing his junk, and it was caught on surveillance video. The guy made his way into Madison's Weho home, stripped ... then grabbed some Q-tips to clean…