Maybe a simple index of whether the meters generally meet their spec...
I think this would be great, if say, you don't recognize a Fluke from a whatever... Some indication of general "trustworthiness" would be helpful since I only recognize one to two brands.
I just spent some time doing my home style "calibration". I bought a DMM check and in short, my 30 year old Fluke 8050A's spec'd to be about 0.1% accurate, look to be more like 0.01% accurate after 30 years. Some cheap UEI meters are much newer, and at the edge or just outside their specs of 1%.
Most of these meters are from reputable companies. Some of them come standard with calibration certificates or as an extra option.
You can generally work on price. The few meters from less well known companies, selling for less than 150$, are the most likely to drift over long periods, as they tend to use cheaper components.
Among those, I can only vouch for the UT71 series, two of which I test regularly. My 61E, unfortunately, didn't fare so well.
Most companies still recommend an annual calibration for their meters.
New file: A few more Fluke meters added to the list.