What is the ruling on exposing companies that deal in unlawful transactions, or have bad dealings, or offer poor products? And what is the ruling on offering advice to one company over another, and warning against another?

Speaking of companies as if they were individuals is only permissible with truth and fairness. What is forbidden among them, such as usurious banks and commercial insurance companies, it is obligatory to warn against dealing with them, to clarify their religious ruling, and to advise those in charge of them to repent. As for permissible companies, it is not permissible to warn against them. If a defect is found in them, it should be mentioned specifically if the interest (maslaha) dictates it, while clarifying what is better if it exists.