I’m not quite face-blind, but on tests of facial recognition that I’ve taken (such as those here) I have performed worse than average. How much worse is unclear. My guesstimate is that I am about one standard deviation below the median, i.e., at about the 15th percentile, on face recognition. This is low enough that it’s obvious to me that I have trouble with faces, but not so low as to be obvious in my day-to-day interactions with other people, except in some circumstances. In general, I have trouble with the following:

• I’m often unable to mentally transform faces based on differences in level of facial hair (e.g., shaving off a beard), makeup, and hairstyle. Often, I have a hard time performing the mental transformation even after I know that the two faces belong to the same person.
• I often confuse between two specific people who when put side by side look somewhat different, but for whom I can’t come up with a clear verbal marker to remember who is who, i.e., they have similar sex, skin color, hairstyle, height, build, etc. This is partly because I often use my verbal memory to overcome my low natural level of face recognition, for instance, I remember that “Mary is the tall girl who looks Chinese/Korean” rather than actually remembering Mary’s face.
• I used to selectively blank out on mental reconstruction of faces of people I know and meet daily, even though I can recognize them if I do meet them. This happened a lot to me during my school days. It’s less frequent now, thanks to Facebook.
• I often don’t recognize people by face I haven’t met for a long time, even though they recognize me, and I either need to ask them bluntly or wait for them to speak or engage in some other action that I can recognize.
• I find it a lot harder to recognize people based on photographs as opposed to recognizing them based on seeing them in videos or in real life. This suggests that much of my recognition is based on mannerisms and speech style rather than pure appearance.
• For a large number of public figures, I have only a vague idea of what they look like. The exception here is actors and actresses whose movies I’ve watched regularly.

I generally overcome my poor face recognition problems as follows:

• I use verbal memory to substitute for poor face recognition: I’ll connect the person’s name with broader markers such as sex, height, build, skin color, hairstyle. Thus, controlling for the size of a gathering where I need to remember people’s names, the more diverse the gathering, the better I perform.
• I might also rely more on people’s non-appearance-based factors such as aspects of how they carry themselves (gait, facial expressions) and how they speak (accent, intonation, pace of speech).
• I sometimes go through a person’s Facebook photo album in order to familiarize myself with how that person might look in different settings (different levels of facial hair, makeup, and hairstyle).