Did you ever have a marketing campaign for your practice disappoint you? How about a total flop? I don't know anyone who has not wasted a small fortune on failed marketing campaigns at some point in their career. I've certainly had some that only had what advertisers call a "dead cat bounce". Ouch!
However, before you decide something silly like "post cards don't work for me" or "Facebook does not work", take a look at this video.