Although physical appearance should not be playing a role in a person's professional life, sometimes it can have a negative impact on someone's chances of getting a job. Sometimes discrimination is intentional, but most time people don't even know they're doing it. They just think they're giving the job to the best candidate, not the person who showed up with the clearest skin.
There is a well-known concept in psychology called the "halo effect". It means simply that people tend to attribute positive personality characteristics to good-looking people. So, conventionally attractive people end up having it easy at work, in school, and in other areas of life. No, it is not fair, but that is simply the way the human mind works.
If you have a prominent facial "flaw", such as a scar, birthmark, or something similar, you may have already suffered because of it without even knowing. Ever been to a job interview that you thought went great, but didn't get the call? Maybe it was not you, maybe it was them.
The "halo effect" entails people having prejudices against those that do not fit into their view of what is beautiful. People who fit into that view are instantly judged as more intelligent, more efficient, more hard-working. Although someone's facial blemish says nothing about a person, in the eyes of employers, it might be that little detail that costs you the job.
So, what is the right course of action here? There is really no one correct answer. You could decide that working for someone who judges people based on such a minor detail is not for you anyway, and be happy that there is such an easy way to detect such people.
If you notice the interviewers glancing at your scar during a job interview, you could choose to address it. You could tell them how you got it, and what it means to you. Give it a meaning beyond just a facial imperfection. Once you talk about the elephant in the room, it will go away.
However, you can also try fixing your small facial "imperfections" with simple, yet effective cures. Try nurturing your skin with some nutritious products that can decrease facial blemishes you have. Sometimes a little cleansing and moisturizing can do wonders for the skin. Skin care is very important for overall beauty and a healthy, clean look of the face.
Even if your scar or birthmark are still showing, they will be less of an issue on an otherwise well-nurtured skin. They might even add some charm, or become your distinctive characteristic. In any case, skin care will help you use the "halo effect" to your advantage. And that cannot be bad, right?