If it’s medical info, there really isn’t much that I can’t listen to and have some sort of info or advice to give (mostly consulting a doctor or looking at Prevention Magazine or Mayo Clinic’s website for more info). With medical conditions I always want to help and do what is best for the patient.
With sexual exploits, I would feel mostly out of place with anyone other than close female friends revealing info and I would let the “offender” know so.
Some people may “inadvertently” offend others simply by divulging medical problems, but once you yourself, or family members have suffered cancer or bowel disease problems, you have no idea of how much awful problems people have to go through (some painful, some embarrassing, and all very frightening). If you feel uncomfortable or ignorant, please tell your friends/relatives that you really don’t have any info/authority to offer an opinion, but please don’t tell these folks that their conversations about their ailments are boring or gross to you. You never know when you, yourself might suffer from some horrrible ailment or disability.
Sexual exploits, on the other hand, are not really valid conversation, except between the sexual partners themselves.