I have what is probably a close spiritual cousin of one of those, and while it even touts a power factor display, it also loves to show ridiculously high values during idle consumption for anything involving some sort of power electronics (not just for my computer, but for example for my washing machine, too – it shows sensible values while the heating element runs, or when the motor actually turns, but in-between it shows nonsensically high values).

It is a few years old, though, so maybe by now quality standards have improved even for those kinds of cheapo-meters…