Growing up my uncle was a traveling salesman, when I try to explain this to our boys, they cannot imagine a world where such vocations existed. I fear that today going door to door trying to sell things will absolutely just get the cops called on you. And for good reason. I don’t want random strangers knocking on our door any more than the next guy. However not that long ago my uncle supported his family this way, going door to door, street to street, neighborhood to town, selling his wares plus collecting a commission. For multiple years, when I was very young, he sold air filters. In the late 60s a/c units were just becoming truly widespread, almost every home across the country had one. A lot of people were so unfamiliar with air conditioning that they were not even aware of air filters needing to be updated on a regular basis. So my uncle did pretty well selling air filters directly to the consumer, plus in multiple cases showing the customer how to install them. However today you can buy air filters for your AC almost anywhere, even our local grocery store has them in stock. Back then it was much more of a speciality item. It is a good thing that he retired long before large box stores such as Home Depot sold AC filters for only a few dollars compared to what he used to sell them for. My uncle’s timing was very good. It’s interesting to note that something as easy as an air filter for your AC unit could go from being a speciality item to being so common.