In my experience, they seem pretty immune to "garden variety" power surges and spikes (motor startups, etc.), but a nearby lightning strike will often take them out unless proper surge protection is provided at the entrance panel.
Older units also tend to generate wideband RF noise when in operation, which can wreak havoc with radio reception. Not a real problem with strong signals on the AM or FM broadcast bands, but trying to use these things in the same house as a shortwave receiver or ham radio is a recipe for frustration.
