There is no meaning attributed to the intensity of a line. Even synthetic urine controls (which contain no drug metabolites at all) can produce a faint line on an assay. A faint line is still a line, which is a negative.

If youre still not convinced, you can always substitute for the actual U/A, using the clean urine of the person whom youve given your last home test to. Subbing is easy on a DOT test in that DOT tests are unobserved unless you had been suspected of tampering.