Open Spotify -> Login
Edit -> Preferences
Click "Connect to Facebook"
Login to Facebook with your user credentials.
Click "Add to Facebook"
Open your browser and Log into Facebook.com
Click the upside down triangle shaped icon -> Account Settings -> Select Apps on the side
Click Edit beside Spotify
Under "Who can see posts and activity from this app on Facebook?" Select "Only Me". Click Close.
What this means is now when Spotify sends track info into Facebook, Only you can see it.