I thought I'd run a reading-age checker over Facebook's Terms. I did not include the onerous "other terms and policies" because they are only available as separate documents. (It is curiously tricky to just get all the terms you sign up to in one place.)
The Flesch Reading Ease level is 39.6. This is the middle of the "College Age" range (30-50).
It seems to me that any Terms document should be written at the reading-age of the youngest people you allow to create accounts. Facebook's is currently thirteen. (I am assuming of course that all people over college age have a reading level that reflects that. They don't.)