My take on symptoms of 'Dirty power'.
RFI - Harsh sound, Grey background, Sounds that blur with each other.
EMI - Weak & untight Bass, Small stereo image. Missing the Boogie Factor
Leakage currents - short decay of sounds, obstructed sound (can be minimized with correct phasing of equipment)
Too much shielding - splash sounds on cymbals, congested & choked sound
DC - Missing Oomph, Tiny bit of distortion on the transients. General lack of naturalness. Bassdrum that sounds like 'Bonk' instead of 'Bup'
General observation: More capacitance = less high, More induction = less bass.
Love to hear other peoples descriptions.