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.
Just a guess, but I think some electric utilities generate their power using low quality electrons. LOL ;<))
Hard to say how to tell if you do not hear any flaws.
Low voltage is easy to spot when a motor (like frig) kicks i and the lights dim..
Dimmers and other noise on the line? poor black levels/silence between notes. Same for TV, a HD TV can show a lot of grain in the background (over the air picture via antenna, Some cable co. the grain is their trash..)
Personally i do not think at your level a little flaw in the power is going to do a lot. Fixing it would cost too much for the little improvement.
The money would be better spend on better electronics.
Ditto fancy interconnects.. Why spend a lot on them when the money would do way more on basic components.
So stick with the cheaper solutions you have tried.
And save your money for music.

(one super cheap add on tweak is to place a 15 watt/25 watt light bulb in the wall duplex just before your equipment, or in the power strip, or whatever,,
So it acts as a 'buffer' it will suck up the 'noise' as good as any $50 noise harvester..
Whatever.. so it is just before the cords for the equipment
So use one outlet in the wall for your gear, and the other get a small plug in socket, or an ordinary lamp (no cord is best, so the plug in with the screw for a standard bulb)

Another worth while thing is to replace the old duplex in the wall with a $3 or so heavy duty Pass & seymour outlet from Menards. (Levitron totally SUCKS, so skip Home Depot!)
There's equipment that logs power data. It's not cheap stuff but its accurate.
I was advised by Almarg to use a voltmeter to check and see if and how much my power varies from an earlier thread. It turned out my power never really varied by more than 1v all day long.

I would think this consistency would indicate pretty good power straight from the wall socket (I live in an apartment in the San Fernando Valley). I just use a Brickwall surge protector and everything seems fine.

The only time I tried a power conditioner was a long time ago and it constricted the soundstage and dynamics (I forget the make but it wasn't expensive).

From what I've read here, and elsewhere, only you will know if something works for your system. You should be able to get a loaner from some of the vendors out there to see if anything makes a difference. You'll only have the cost of shipping it back if it doesn't work.

All the best,
I like Elizabeth's lite bulb trick. But I think you need surge protection as you have mentioned and it should be hospital or professional grade. There are strips that provide RFI and EMI filtering which is important. I have very steady line voltage and I use a Furman SS-6B Steel Power Strip to my amp.
Elizabeth, your comment about dimming the lights takes me back to when I had a heftier system in the 70s--in one house I in which I lived the lights would dim whenever I switched on my power amp (McIntosh 2300).
When I bought this system I installed an upgraded outlet system for the sound system. I use one plug for the integrated amp and the other for a strip with the rest of the stuff (I wish I had another dedicated plug for the sub, but so it goes).

I'm leaning towards a strip that's consistent in price with the rest of the system (unless someone can convince me that I need to worry about dirty lines).

Thanks to everyone who has taken the time to respond. This helps a lot.