Only during long term use in cold winter camping. Even with the vents open all day it still accumulated under the body of the camper. I could feel a lot of moisture in around the shell by peeling back the insulation above the HappyJack control board. The control board stopped working and saw moisture dripping off of it. Next I noticed a cab over side bulge or delamination developing. I have since repaired. Generally speaking the camper needs thicker insulation as the unit is so cold inside leaving a couple vents cracked all night didn't help. I wouldn't go longer than a week in around teens and below weather.
It would be nice if they would have an option of thicker insulation the way summers are so crowded, more and more folks do cold weather camping.
Warm days I turn on my built in bilge blower installed in the basement which is ducted to blow outside. It helps but don't forget and leave on if temps drop.
