You have an acquaintance named Ivanna whose company you find generally pleasant. Although you are not super-close, you gravitate towards her at parties to chat.
Another acquaintance of yours Alex, tells you that in fact Ivanna is TERRIBLE, insofar as Ivanna has definitely been terrible to Alex in the past.
What's your move?
*Avoid inviting Alex and Ivanna to the same parties, but otherwise don't get involved at all. It's not really your business, and Ivanna has always been perfectly friendly to you.
*Start disassociating yourself from Ivanna, because a friend says she's sort of awful.
*Launch a low-key investigation by seeing what other people who know Ivanna think of her.
*Some other thing.
Possible answer-changing factors:
*Maybe you are closer to and have a longer relationship with Alex (or Ivanna).
*Maybe you have many friends who love Ivanna's company.
*Maybe Alex isn't the first person to say that Ivanna can be mean behind closed doors.
*What is Terribleness? (A single horrible incident vs. repeated infractions)(unnecessary rudeness vs. racist comment vs. screwing things up for a job opportunity vs. anything physical)