Q: Can I post a fictitious “rate this seller” review on Amazon.com et al. that applauds my own company or discredits my competitor’s company?

A: Posting a fictitious comment applauding your own company is deceitful, even if the information is correct. It might also involve geneivas da’as (misleading people), since readers expect such comments to be unbiased reports from customers and decide to make purchases based on them (C.M. 228:6; Tzitz Eliezer XV:12). Instead, you should encourage customers who had positive experiences to post reviews.

Posting a fictitious comment discrediting your competitor is motzi shem ra, a severe form of lashon hara. In truth, any person has to be careful when posting a negative review. The reason to allow doing so is the need (to’eles) to warn other potential customers about dealing with that company. The Chofetz Chaim (Rechilus 9:2) requires that the information be true, without exaggeration, and with proper intent to warn the consumer - not out of hatred or intent to disparage the seller’s reputation. Therefore, a competitor should avoid posting even a true negative review, since it is almost impossible for him to have proper intent.