In our podcast “100 Ways to Fight Obesity,” Steve Levitt and David Laibson discuss the possibility of using tapeworms to fight weight gain. (Seriously.) That prompted a reader named Scott Genevish to send us a real-seeming (?) old advertisement for “Sanitized Tapeworms, Jar Packed” (below). It was accompanied by a bunch of other old ads that are all, from the perspective of 2013, radically outdated for one reason or another. I have no idea if all the ads are real; I’m sure most of them have made the online rounds before. Still, it might be worth a look — especially when you think about how the line between repugnant and not repugnant can shift over time, sometimes faster and more dramatically than you’d ever predict.