Firstly one of the biggest is the Facebook Privacy Notice
Variations about this 1 manage to occur every couple of months, and quite a few intelligent people fall for it.
It says something such as:
The places you publish a paragraph of text that points out that facebook is not permitted to use any of your info on your account, in doing so are violating laws etc. A misconception which requires yourself to post the disclaimer on your account at least once in order to keep your information non-public.
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