My favorite is the client who begins an interview by complaining (or, worse, insulting) their former lawyers. Red Flag! That idiot lawyer who did not know what he or she was doing the prospective client is complaining about could be you some day.
Learning to recognize the signs of a problem has always been part of the learning curve of all new lawyers, but now there's help. Thanks to this wonderful chart prepared by L. Maxwell Taylor and discussed over at MyShingle.com, you too can learn to spot the reg flags. Read the chart carefully and keep it handy. Fill a spot during an interview and you will know how to handle it. Fill more and you are warned. Fill a full row, and you should probably consider asking the client to Go!