Does it fog up in the dome being outdoor where temp is always changing between seasons?
I have never had a dome fog up outside (knock on wood).
The biggest issue is that domes are not recommended outside unless it is well protected from the elements. The big issue is that the domes will hold onto water droplets much longer than a turret or bullet and thus any dirt on it can then become problematic. And during a rain event with IR, the camera is basically blind...
The domes attract lots of dust. Then rain. Then dirty rain spots. Glare from all angles of the sun. Then over time the sun will "fog" the dome like a car headlight.
But the few domes I have that are under a soffit perform fine.
Now a PTZ dome adds another layer to the mix - as it moves around, it has the potential to pick up reflections from any light source, so depending on the install location, one may experience the occasional glare.
Fortunately in the samples Looney provided, we didn't see that happening, so perhaps the design has been able to mitigate an issue from older dome PTZs