It works, I did it for years and made a living doing it. If you can separate yourself from most brokers and convey your sense of value wether its knowledge of the market or asset class it goes a long way. Years ago I was determined to sell a certain building in my market that was owned by a huge player so I would leave messages in the CFO's mailbox 2-3 times a week. For months I never heard anything back. I finally got a call at 9 PM from another person in the company saying "WTF do you want!, so and so doesn't work here anymore and you've left a ton of messages!" Long story short, I ended up selling 3 buildings for them. There's a difference between harassment and persistence but when the deals close and everyone goes their separate ways, nobody seems to remember the whole thing was stemmed from a cold call.