I don't know, some how I feel like all the plots are generated in a factory far, far away from the rest of society. Deep in the badlands, a computer spits out American Dad scripts day and night. Unfortunately, the computer has worn down from decades of neglect, and the scripts it generates have gotten increasingly worse.
There was once a joke in MAD magazine, wherein American Dad writers were digging through a dumpster for thrown out Family Guy scripts. I think that perfectly describes the most likely alternative.







