Back in the late 300s, the big heresy was Donatism. The basic idea was that if a Priest cracked under the pressure of persecution that it somehow "proved" he was never really worthy of administering the sacraments in the first place, and therefore any baptism, eucharist, or other thing he administered was somehow invalid.
Augustine, however, issued a powerful defense of the idea that a sacrament doesn't depend on the one administering it, but rather the one receiving it. In reading a recent question about the Waldensians, however, I was surprised to see that they really were much-later Donatists.
The question then, is this - Are there any modern / extant churches that subscribe to this?