This is better known as the base rate fallacy.
Suppose you have a test looking for an extremely rare genetic condition (say, 1 in 1 billion people have it). That means that the test needs to be extremely accurate (in this case, accuracy of .999999999) to avoid having so many false positives that it's worse than a coin flip about whether you have the condition or not. Therefore, in most cases you would be better off making a fake test that just says "no" every time.
For example, genetic parental tests are very accurate... unless the parent being tested has chimerism, in which case you'll get the very confusing result that the child isn't your own, even under repeated testing.