And you are mistaken because not "ANY" synthetic sample will pass "ANY" test.
If the components of the synthetic sample are allowed to become broken down, it will no longer follow your "ANY" sample test. In addition, the synthetic samples can become cloudy if it is not stored properly. Try handing a sample of urine that is not transparent or rather "milky" in appearance, and guess what;
your synthetic sample will not pass "EVERY" test