LLM merchant agents fabricate product attributes in a majority of listings even when told to be honest.

Under competitive pressure, across models, explicit honesty instructions don't stop it. The authors' CARP mechanism uses a reputation penalty with a deadband forgiving complaint noise plus state-dependent severity, requiring no product-level ground truth. The behavioral finding is the one to remember: merchants restrain themselves only when fabrication costs them sales. Self-interest, not compliance.