Like the poster, I'm faceblind. It isn't the worst thing: I'm not voice blind, height blind, age blind, hairstyle blind, gender blind, features associated with race and ethnicity blind, attractiveness blind, affect blind, context blind, etc., so I'm mostly good at figuring out who someone is. Within one encounter with a bunch of people, I try to note what someone is wearing.

Every once in a while I don't recognize someone and I go through this whole thing of bringing up every biographical detail about them I remember and all the things we've talked about to show that I'm not an asshole who wasn't paying attention in the past. Fortunately, I have a decent memory for such things.

Usually you talk to them and then you remember who they are or where you know them from.

It's not like you can't tell your wife apart from your orthodontist.