Contrary to popular belief, a faint line is no indicator of a person "barely" passing or not. Even synthetic urine controls, which contain no drug metabolites at all, can produce faint lines on an assay. A faint line is still a negative. A negative is a negative.

Even if an untrained tech were to misinterpret a faint line as a "fail", and sent the sample off to the GC/MS, the sample would still come back as a negative.