I would imagine Facebook sources are very vulnerable to law enforcement unless they have incredibly tight operational security.
So, ask yourself... What precautions are they taking to protect you and themselves from investigation/arrest? Are they using an email with PGP or end-to-end encryption? Do they take orders via Facebook? Are they a source local to you or delivering nationwide?
There is a chance that ordering from a Facebook source would get you legitimate AAS. However, I believe the chances are much lower than sourcing from other clearnet sites, forums, etc.
Finally, I would consider Facebook to be an intolerable safety risk for a plethora of reasons. Be patient, do your research here and at other sites, find a source you want to gamble on, and then place a small order and try them out.
