Many years ago when i was an aprentice, a chap i worked with bought a cheap second hand bike, working in a steelworks some of the other chaps decided to fill the frame with iron pellets about the size of small marbles, this increased the weight of the frame quite considerably, and they persuaded the chap the bike was just well made, not a lightweight bike like mine.
Another time, while in college, somebody tied a piece of string onto the inner tube in 2 places about 4 inches apart, then blew up the tyre, when the tyre was on the bit between the strings it looked like a flat, but anywhere else it was fully pumped up,but when ridden it gave an extremely unusual ride, especially on corners.
Have also been told mtbs would never catch on.