The biggest issue with the FB police is that they don't like anything that is a weapon. I've had a few selling posts that were blocked because they had the word "Knife" in the post. I've even tried without any reference to knife, blade, etc., but they still got blocked. It seems to be a little random as far as the enforcement. Follow the advice above to treat it as a social place that gets your knives in front of eyes. Instagram is kind of the same deal.
I have my Instagram linked to my Facebook page so when I post on Instagram, it posts on my Facebook page also. Anytime I put for sale, available or such, it gets blocked by Facebook and doesn’t get posted there.