Whats a good economical way to test the electricity on a circuit?

Not nearly as discerning, but- there’s this type of, "sniffer":         https://www.amazon.com/Digital-Display-Tester-Measuring-Instrument/dp/B082M1BBG3

Oscilloscope for time domain, FFT analyzer for frequency domain, and LISN for what comes out of the power cord of equipment. They are not cheap but that's the only way to visually see/measure noise.

I don't think smart meters are bad, I think they collect a lot of information and STOP, meter readers in their tracks. I really think that is what it's all about. Smart meters cost a LOT of folks their jobs and as a results few EVER come by to check.. That leaves a simple visual inspection of your equipment, unattended.

500.00 meter. 100,000.00 (with H/W and retirement package) per year employee. LOL

Again, you already know it's dirty, and needs maintenance. 300.00 usd and you don't have to check or worry. It checks for you in Milliseconds and responds in milliseconds.. Mine tell me what they are doing, My server monitors the, backup system for the server its self, and any parameter I want to monitor. Hi/Low voltage peak, amps drawn, interruptions, time stamp, WiFi reboot or shutdown...

Most laptops can monitor all that stuff, if you want...Can't fix it though...

Regards

Don’t waste your time and money on measuring noise on your audio circuits. They are all noisy to a certain extent. If you want to make sure you have the least noise on your audio electrical circuits,  just hire a qualified electrician and install dedicated circuits and audiophile grade AC outlets (Furutech).
You should wire 2-3 dedicated 20 A circuits, depending on your system configuration. I have 3 dedicated circuits, one for each of my monobloc amps and another circuit for my source components. On the source circuit, I also added a Shunyata VRay II power conditionner.

For my own information, I purchased a used Entech AC line analyser meter. Measured the dedicated AC line noise on my dedicated and non-dedicated AC lines. The dedicated lines had 98% less noise than the non-dedicaged lines...