Dissonant Technomancers are the equivalent of Toxic Shamans. While a normal TM hears the Resonance of the matrix and the code and all that, a Dissonant TM hears the Dissonance. They hear the corrupted code, the registry errors, the malware and so on.
Deus did not use Dissonance to corrupt his pet TMs. He took some naive children, told them that he was God and that they were His special Chosen. He gave them purpose and pride and power, when they likely had been living in squalor, as most Otaku tribes did. That isn't dissonance, that is old school cult leader shit.
Pax, on the other hand, discovered Dissonance in her quest to stave off her Fading (when Otaku began losing their powers), and began corrupting others with its influence.