Unfortunately, not all critique groups are created equally, and it's not always easy for a new writer approaching their first critique group to separate the helpful from the harmful.
A good place to start is to read Anne R Allen's Beware Groupthink: 10 Red Flags to Watch For When Choosing a Critique Group. I've listed the bullet items here.
10 Things that Can make a Critique Group go Sour
- Dogmatic PC/Religious Policepersons.
- Misinformed and outdated "writing rules"
- Unenforced Rules (or None)
- No moderator (or a bad one.)
- The grammar militia
- Power-trippers and divas
- Know-it-Alls (Who Don't)
- The Empathy-Challenged