Self cleaning oven?

Hmmmm...this is a mystery to me. I decided to clean my oven today. First I wiped it out...that wasn't gonna cut it. Then I used my steam cleaner with the help of Andrew. That was good, but not good enough, so I got out the owners manual and read. It said not to use oven cleaner because it's a self cleaning oven...sounds easy, right? So , I followed the instructions for a three hour cleaning cycle. Then I lit a couple candles. Then I turned on every fan in the house!! Still the funky smell prevailed! When the cycle was about half way done Andrew started coughing (He was back in the playroom) and I knew I should get the kids out of the house. I stopped to consider the danger of leaving the house while this "cleaning" process continued, but decided the health of my children was more important to me than the rare chance of something exploding in my kitchen. So we went to Target (naturally) to waste the afternoon. So here is the mysterious part... Where did all the burned on spots go?? All the gunk I couldn't even budge with a steamer???? I thought I would at least have to wipe something out when it finished, but no, it was perfect! The oven looked brand new. So I guess it really is self cleaning and if you survive the funky smell it's worth it.