When I meet people, I always find a distinct physical feature to remember them by, such as eyebrow shape and voice, rather than clothing. Voice is quite reliable; it has prevented a lot of potential embarrassment.

If a person does not have any kind of unique markers on them, I will not recognize them or I will have great difficulty, even though I have met them previously. Even recognizing family is a problem, especially if they have changed their appearance.

I have not been 'officially' diagnosed with prosopagnosia, but my doctor suspects I have it.