Heck, even dirty power from the wall can contribute. I've seen improvements in stability from putting things behind power conditioners.

Definitely that too, particularly in 2nd-world countries. I remember having a difficult time with dirty power for some hardware products I was responsible for at one time, where the customers were in the Middle East nd Africa in the 1990s. We ended up having to have the PS manufacturer do a redesign to help compensate for dirty power. It can be done, but it costs a bit more.