Can sleep apnea tests ever be wrong?

Yes, it's possible: Most attended sleep studies (where you spend the night at a sleep center) are very accurate. The take-home types of study are helpful for screening, but not nearly as much data or accuracy. That being said, all sleep studies are flawed to some extent as we do sleep differently on different nights. Repeat studies are the best, but at additonal time and expense.

Possible: The onsite sleep labs are generally accurate, however there can be a lot of variability on the home sleep study test.