Secrecy is a great thing to have with your business. If your product or service is a secret, it makes it special. Special because people love to find out secrets. And if someone calls your restaurant, bar or shop a "best kept secret", you know you're onto a winning formula.
I first learnt about secrecy long before I knew anything about marketing. It was years ago while watching an episode of Beverley Hills 90210. The one where Steve Sanders walked into a grocery store to exchange an egg for the secret location of a rave.
Now I'm not a fan of 90210, Steve Sanders, or raves for that matter. But this example explains the magic of secrecy. Part of the reason why underground rave culture is so popular is because people like being part of the 'in' group, that knew the secret of where the rave would be. Simarly, mobmov works because you have to sign up to find out where the drive-in will be.
In Melbourne you can visit dilapidated buildings that are used as public art spaces. But the venues aren't advertised. You just 'find out' about them through word of mouth. Again, that's where the magic lies.
But once the secret gets spread too far – that magic is lost. So the key to marketing secrecy is that you need to avoid 'selling out'. Which is fine for some us.