Here are the first test results. I earlier stated that the voltage from positive or negative of either device to earth ground was zero volts; DC should be appended. Yup, forgot to set the DMM (Agilent U1241) to AC.
Load testing was done with a BK 8540, and voltage readings are from the BK. The real one has a stated capacity of 0.85 A; the fake has a stated capacity of 1 A. Each was tested within the range of its stated capacity. See the pic below for the results.
The fake gave up at one half of its labeled capacity. And no, it didn't die; as soon as, the load was lowered back to 0.5 A or less, it provided the same output as previously. A little surprised at the ~10% drop by the real one. In my experience, full-size SMPS-type wall warts usually maintain voltage better than that throughout their power range. Guess there is a reason for the larger caps and inductors in them.
To check AC leakage to earth ground, I initially used a 2000 ohm, 10 watt wire-wound resistor from either the positive or negative output to ground and measured AC voltage drop across it with the Agilent DMM. When it became clear that currents would be in the mA range or less, I used a 220 ohm (measured at 218.4 ohms with the Agilent), 1 watt metal film resistor.
The mVAC drop was divided by 218.4 and multiplied by 1000 to get uA. As can be seen in the table, the fake had higher leakage to ground than the real one, but neither could be considered dangerous. For both devices, leakage to ground was similar for their respective positive or negative outputs. I also checked frequency of leakage with the Agilent and was surprised at the results because I was expecting 60 Hz. For the fake, the leakage frequency was in the kHz range and varied with the load put on it. For the real one, frequency fluctuated from zero to 10 Hz (not kHz) at each load setting.
VDC across the resistor was checked with the Agilent and was zero for either pole of either device with any load setting.
Before I open the devices, I want to check between outputs and outputs to ground for noise and ripple with the scope. Hope to get to it soon.
Mike in California