When I first moved in with my SO, he lived in a pretty crappy apartment. The bathroom had really poor ventilation and so the walls were always covered in mildew. It had an AC unit in one of the bedrooms, but you couldn't turn anything else on when the AC ran. The bedrooms both had south-facing windows, which meant they both turned into tiny ovens in the afternoon as we were also on the 3rd floor. We had a balcony, but the roof covering the balcony let little sunlight into the north-facing windows of the living room, which meant most of our living space felt like a dark cave.
And when I cleaned that place, I always felt like I couldn't get it really clean. Even when we moved out, and I gave the whole place a good scrubbing, it still felt dirty.
We were sooooo glad to get out of there! The townhouse we moved into after that wasn't the greatest, but it was a significant improvement. And now we live in a super awesome house