How do you figure? Wouldn't you attract more candidates (both good and bad) who are drawn by the high salary figure?
Most job posts I've seen list a salary range or (more often) just note that salary will be commensurate with the candidate's skills and experience.
As I think about it, I don't think you can do much to weed out lesser candidates at the job posting level. Often people who aren't quite qualified don't know it anyway. I would just focus on writing out the requirements as dboarman suggesteddboarman suggested to increase the odds of attracting qualified candidates.