Loss of control
Lesson 2: You do not have any control over Facebook.
Aside from not knowing what might invoke Facebook's account disablement, there are other factors you don't have control over. When Facebook changes its layout, you have to fix it. When Facebook is broken, you can't fix it. When Facebook changes its application programming interface, you have to reprogram yours.
We built a social media monitoring application for the sports industry, called Sports Fan Graph. The system requests fan counts from Facebook once a day for teams and then monitors their growth on both Twitter and Facebook.
Without any notice, Facebook decided to rename some of the fields we were extracting from its Open Graph API. The client called us and asked why its application was broken. We had to stop everything, figure it out, and then fix it. This is inexcusable in the software-as-a-service industry.
An additional hole in Facebook's use is that you can tag anyone or any business on any place or in a status update, and that entity is notified. Some of my friends do this to notify me of a video, photo, or site they want me to look at. It's annoying. If I'm tagged, I should have the opportunity to review and approve that tag before it goes public.