I found a legit pair of moggles next to a skeleton, so I tried them out in the ruins, and the darkness vision you get is still washed out as if full daylight were present, even in a room with no light at all. If it were a room with one of those ceiling holes that lets daylight in, I wouldn't have been surprised, but this room was pitch black dark.
Steps to Reproduce
wear moggles in totally dark ruins room during daytime
wear moggles in totally dark ruins room during daytime