Realtor and Consumer Survey.....What was your worst experience?

I am taking a survey for Realtors and Consumers....... Realtors - What do you believe is the worst mistake you have made or even expierenced in the past with your buyers and sellers? Consumers - I want to know what you think makes a great Realtor, whats your expectations and what has your worst expierences been.... Granted no Realtor is perfect, however I am doing this survey to get advice and stories on what people really think about Realtors and the mistakes they believe made for a terrible expierence. Everybody's comments are greatly appreciated!!