The story of how potatoes came to be called spuds is a mundane one. As if often the case with such boring word origins, a fanciful explanation for the derivation of spuds is often given. This explanation is owed to the potato once being a much-maligned root in Britain and Europe. In fact, when the potato was first introduced to Europe via the Spanish, in the 16th century, it was only grown as a curiosity in botanical gardens. As for food, it was considered only fit for pigs and, perhaps, poor country folks.
The fact that it was a member of the deadly nightshade family didn't help, and the potato was blamed for many ailments, including tuberculosis, rickets, and syphilis. Perhaps not too far off the mark, it was also said to cause obesity, but, in addition, the potato was even blamed for war! The Russians called it the "Devil's Apple."
You know what professional cook cares whether the tomato is a fruit? Because I'm not aware of one. We have a great misconception about fruits, but here is one thing that can set you free of the chains of grade school science pushers: There is more than one way to classify a vegetable and the way we classify them in the kitchen has nothing to do with botany. I guarantee you that a botanist is not going to lose any sleep over a cook placing a tomato, or anything else in the 'vegetable' category because it makes more sense for cooking.
Or is it just hokum? The importance of the sense of smell in informing our taste is a subject that fascinates biologists. Most high school biology texts include an experiment designed to test just how important our sense of smell is in how we taste things. The experiment involves peeling and cutting up apples, potatoes, onions, and/or celery into bite sized pieces and then blind-folding people and having them taste the pieces at random with their nose plugged so they cannot smell.
Bananas are difficult to digest. This myth was being circulated in the early 1900's and probably earlier. The belief shows up in some health and nutrition books of the time, but whether the myth was inspired by the books, or the public belief was repeated by the authors without any investigation, is not immediately apparent.