The basic trust we grant every mitzva-observant Jew applies to normal situations in which one person hosts another. Yet, commercial venues require rabbinic supervision because being honest about kashrut may cause them to lose money. For this reason, the temptation to be dishonest is greater. Therefore, people should not eat in any restaurant or hotel lacking supervision. Generally, kosher supervisory agencies provide their clients with a certificate attesting to their kosher status. Before eating anywhere, one should confirm the certification is valid.