What are some of the mistakes, failures or bad purchases of your audio history?

Kind of the opposite of "best of".  I, like most, have made some mistakes or purchases that were poor choices. 

The worst were some speakers "I built".  Anything I owned that was "quadrophonic", Lamp cord for speaker wire, BSR turntables...yes they were in my "poor just home from Vietnam" days...but still.., early Japanese receivers that were not much better than appliances, ...and even though I got into some of the best in later years, some of my beginnings were more bad than humble,...but my taste in food, friends, mates and many other "things" went through what can kindly be called a "learning curve".