What genuinely useful thing did you learn from a Reality TV Show?

Mine was from Pawn Stars and relates to valuable books from the late 19th century.

They said that one way to tell a first edition of many of the most famous (and valuable) books now from that period such as Dracula and Dorian Gray, was that the covers will always be yellow. Yellow was the colour that a publisher printed in, when they wanted to make a provocative statement.

Sounds trivial but it is exactly one of the things to know, if you somehow come across one in a charity store or at a car boot sale. Might be the difference between a book worth £10 and £10,000.