Good power/Bad Power

What are the causes, symptoms of bad power? I'd rather use a simple surge protection hospital grade strip rather than a power conditioner if my power is clean. How can I determine this (short of trying a multitude of gear over a long time)--is there a test for clean power? Is there a more or less likelihood of it (given my environment--1960's neighborhood in the 15th largest city in the US, FWIW)?

My system is low-budget (NAD C320BEE, Dynaudio 1.3 MkII, REL sub, plus CD/TT/Tuner--and, in the last week I've swung from power condtioners (OneAc, Powervar, etc) to strips (TrippLite, Wiremold, etc.) so I won't be getting anything
well into 3 figures or higher.

Thanks, folks.