When you sign up for a Facebook App you may unwittingly allow it to have a level of access so it can write things on your wall.
Some have signed up for an Astology App that every day posts their horoscope to their wall. This is a benign App.
Some devious people have found that they can lure you to sign up for a Facebook App that promises things that dont work, or an App that doesn’t do much but they get you to agree to let them access your Account. Often it will only allow you to use the App if you agree to this.
What can happen is the App maker can then post advertisements and other rubbish to you wall and you may not even notice it is happening. Often the posts they make lure your freinds to do the same thing and give acces to their accounts.
Here is how to remove the ability for an App to post to your wall or remove it all-together
Click on Account at the top right of the page, click on privacy settings
At the bottom of the page on the left it says “Apps and websites” click on ‘edit your ‘settings’ just below that. On the next page there is a section called “Apps you use” and to the right there is a button called “edit settings” click on that.
You should now see a list of the Facebook apps that you have signed up for. To the right of each name there is an ‘edit settings’ link, click on that for each one and you can choose whether you allow that app to access your details or post to your wall.
You will see that some say ‘required’ that they post to your wall. I consider deleting them unless you are happy using them. You will see a link on the right near the top that says ‘Delete App’