I have glasses. The only time they fog is when they are cold, and you walk into a warm room with enough humidity that the glasess cooling the air reduce the air capacity to hold water. You see condensation on a glass of iced tea, not a cup of hot coffee. The only other time is when the humidity is very high and the item is lower than ambient temp. (Hot breath on cooler glass).
The point being, you are less likely to get condensation on the inside of the camera where it will be above ambient temp. If it is outside there may be some dew (due to the air cooling at night, and thus reducing its ability to hold moisture (making the relative humidity go up, and when it gets to 100% you will get fog/dew).
As Carlos says, if you took a camera from the outside on a hot humid day, and then took it inside an air conditioned room, the case would drop temp and the hot humid air inside could condense. Or if you had a cold front come in on a hot, humid day, it may cause similar internal condensation.