The manufacturers claim that it was it was one of the ingredients in the formula that were adulterated and they didn't know. But, they should have picked that up in their testing.
However, quite apart from that the fact that they should have identified the adulterant, the product itself could never meet their claims without it. They suggest that the product is as good as Viagra but that is impossible without a chemical additive such as was found.
There is no natural substance that can give immediate effects such as Viagra... although there are natural ingredients that over time will help negate the need for such a supporting drug as Viagra.
So, was it a genuine mistake or a deliberate case of dishonesty? You are best to judge that for yourself, but if it was a mistake then there is certainly a case for incompetence.
I have to say that this sort of thing annoys me. This type of product will not work and consumers should not be misled. If a man really needs something like Viagra it is best that he buy the genuine product and knows what he is getting. But... with a sensible supplement regime and a good lifestyle it should not be necessary.