Well it seems, rather than a skill needed, its more of a commitment to yourself that you aren't willing to take a listing that is overpriced because you won't be able to help them. I believe it requires showing them the market asking them where they want to price their home to get them "where they want to go on time" and then... if that's not where you feel the home should be priced, just tell them that unfortunately you won't be able to help them....

 You might be surprised when you stand up to leave what they may say,like " Wait what do you mean?" where you can then SHOW them again where the market is and ask " What about this market activity would have you thinking your home will sell at $X?" Let them defend their price, if they do, they adjust and ask you if you think $X would work!  Just keep the faith, there are plenty of prople who want and need to sell their home, and are willing to put a fair market price on it. We DON'T need to take every one that we are presented with!