Yeah, but that only happens if and when the housing has been cracked. There is a tube that allows heat to escape, so if there is a crack in the housing, it will allow water in and there won't be enough air pressure from the built up heat to push the condensation out.
So, if the housing isn't cracked or if the seal hasn't dried up completely, then that foggy look is just particles of dirt being blasted by the lens at whatever speed you drive. This and the elements and road grime eating the plastic.
I suggest never opening the housing unless you are modding the amber lens by removing it. If you do this, just be sure to reseal the housing and lens correctly and you shouldn't have issues with condensation on the inside.