How do you handle monsters using social skills vs PCs?


I’ve checked the books and can’t find an answer by RAW other than the DM decides, so I’d like to know how people handle this in their games. What happens if a thug tries to intimidate/persuade the PCs? Do I roll vs the character’s skill (and which one) or set a DC based on how difficult I think it is? Most of the time I just describe the monster’s actions and let the players tell me how their character’s react, but the monsters have those skills listed in the Monster Manual for a reason.

What do you think is the best to handle these checks in order for the monster be effective, have the same fail chance as the PCs, and avoiding slowing down the play or making the players feel cheated?