People tend to restrict their movement. Breaking the mechanisms, or stopping the fan, so it can't cool. This melts the back of the nacelle. It's what happens to most that stop spinning.Also- be sure to check reviews of the fan your purchasing. About 5 years ago I was looking at them on Amazon and found several reviews of people saying that the oscillating motor caused a fire or almost caused a fire. Like more than 5 stories of that on each of a few different brands.
I have heard no cases of that with ACI and that's the one I ended up getting, and it's still working but clicking. The other brand I have that stopped moving was VivoSun.