Glengarry Glen Ross

It is not for no reason that all of the cast of characters in Glengarry Glen Ross is male.
The play uses the male psyche as a canvas on which to portray a number of the ills of the human condition: egotism and deceitfulness (as exemplified by the majority of salesmen in the play) on the one hand; the impotence and depressive servility of Jim Lingk on the other. Though the play admittedly covers a broader range of emotions than that simplified dichotomy -- the weariness of Aaronow, the office's odd man out, comes to mind -- those two extremes are what the play contrasts the most overtly.
It seems to me that the target of Mamet's scorn, rather than being simply the businessmen in and of themselves, is the culture which gave birth to them. Part of this comes through in Aaronow's last statement in the play: "I hate this job." His hatred is not for his co-workers, but for their profession, for the rat race and its treachery. The line that follows it -- Roma's statement that he will be "at the restaurant," his hunting grounds where he can sell so well -- suggests that even after the ransacking of the office, Roma will still continue to do what he always does best: closing, taking advantage of those with weak defenses. In other words, the salesmen's work does not end with the play.