Karen writes about #DroughtShaming (a hashtag created to shame people that waste water):
"Drought shaming and other attempts at informal social control rely on social interaction, specifically our desire to seek the approval of others. If we don’t particularly care if others like us or approve of us we might not alter our behavior."
Do you allow public shaming of members (or non-members) who violate rules (both written and unwritten)?
If you do, you risk allowing public spats that can dominate all group discussion.
If you don't, the community can't enforce social norms upon members. This is a key factor in group cohesion. Members won't adopt social norms without consequence. Without social norms, group cohesion dies.
I'd suggest allow shaming (condemnation) with strong evidence (and a single, published, right of reply). Otherwise keep it to private messages between members.