I do not believe a generator that is putting out the proper voltage and Hz will harm any modern appliance. The output may not be a pure sine wave, probably a chop wave. Still I do not think it will damage any modern appliance. That being said, I would not run "nice to have" appliances like a washer or dryer if I was not on street power. I do not even run my well pump unless I really need water. I can go many hours without water and most power outages are not more than a few hours. (Hurricane would be the exception).