Yes and no. If you dip one of those instant tests in pure water, the line for THC still will not be as dark as the control line usually. But if the line is faint the THC metabolites are reacting with the antibodies, the basis for immunoassay. But like you know it isn't a zero tolerance test, it is a cutoff of 50 ng/ml so a line is a line. If the line can be photocopied or show up on a pic, that is a line. Whether it is for employment or probation, any "non-negative" result should be confirmed by a lab test.