you just...answered why it wouldn't work. If that much garbage is actually coming into the conditioned power, it will kill the system in very little time.
Why? Is there something I need to know about electromagnetics and primary transformer coils being unable to handle variance in the amperage and voltage?
The DC provided by the PSU is by definition conditioned to some degree -- the transformer does this by using induced current to step down the voltage, then passes it through the rectifier (diode-cathode ring) which should smooth things out even further.
Unless you're saying that if there's enough garbage (read: degree of variance in amperage and voltage, vs frequency of change) to get through the transformer, you're going to kill your PSU, which is true.