We can’t be duped into believing that lashon hara is believable just because it was said in a group or in front of the victim’s face, or if a person claims he would say it in the victim’s face. This gain of trust is the trick of trust is the trick of the yetzer hara, evil inclination because why should the speaker of lashon hara be more trusted and believed just because it seems like it makes sense since why would he stick out his neck and claim something in a group or in the guy’s face if it is not true, but on the other hand this guy being talked about was assumed to be a good upstanding, trusted character until now so how can we decide he isn’t just based on word of mouth of someone else. Even testimony of one witness in court, which is a stronger reason to trust his word is only believable to cause the litigant to swear for some monetary matters, nothing more than that. You are only allowed to be concerned and investigate the matter there is no reason to believe what is heard no matter how believable it sounds and seems to be until you investigate and know for sure it is true. Even if the person who says it can make an excuse that of course what I am saying must be true because why would I say it to his face or in a crowd, even though that isn’t a good excuse to speak lashon hara but it is certainly not a good excuse to accept lashon hara because the people listening still don’t really know if it is true or not.