Was doing a load of laundry in our new apartment. Our washer dryer is in the kitchen (love New York apartments...) and I noticed a bunch of moisture in the kitchen and that it was very warm. Went over to the dryer and felt warm, wet air blowing out into the apartment. Turned off dryer, let it cool, then pulled it back from the wall. Turns out that the exhaust vent was not connected at all. Furthermore, even if it had been, it wouldn't have done any good because the dryer was pushed so far into the wall that it had completely crimped off the exhaust hose.
To make it worse, this is a gas dryer, and it had clearly been like this for a while, so it had just been happily pumping natural gas exhaust into the apartment for God knows how long. Worrying me, I went to check the CO detector and noticed that the world's shittiest painter, who had painted before we moved in, put the detector back on the wall but did not plug it in.
FML. Seriously angry at the landlord right now--this could have killed someone.