SOME generators run clean, others, not so much. I maintain lots of whole house air cooled units, and they all exercise unloaded. That being said, where i live, we have so man6 power outages most of them see real loaded use often enough.
The power outputed by these run most electronics without issue, except for some high end HVAC AND HEAT PUMPS? . Some brands just dont want to run on generator power.
Portable generators is a whole other issue. Ive seen some of these with 25%+ distortion. I would not want to run my electronics on these.