Honours to SeanB! The bridge rectifier in the Maynuo/Atten/BK series of electronic loads might be slightly over rated (8A current capacity, while passing only 1mA), but it is indeed a cheap, bolt-on (to the heatsink) linear temperature sensor. It drives the fan(s) according to actual heatsink temp, rather than load, so the fan is not "hunting" all of the time, like it does in some cheap power supplies.
HOWEVER, there is a GOTCHA in the higher power 300W versions of these supplies, wherein two fans and two heatsinks are used, BUT only the one is monitored by a bridge rectifier (temperature sensing diode). If one fan jams on the unmonitored side, the heatsink will get FLIPPIN' HOT with up to 150W being dissipated and no forced ventilation. The electronics won't pick this fault up, and damage will surely result.
Perhaps UNLIKE the BK loads, the Maynuo I have responds linearly incrementally (that is, the current setting changes by twenty steps, for every one complete rotation of the encoder knob), regardless of how fast you flick it. You can easily choose the size of the step (i.e which decimal position is to be incremented or decremented), however.