The culture of not resigning

Every day one reads in the newspapers that someone high-up in public or private service resigns on being caught doing wrong or saying something inappropriate or even for the mistakes of their predecessors. So we see so many resignations in the democratic countries of the world all the time. Recently the chiefs of two venerable institutions as the BBC and CIA 'walked' voluntarily. Like in cricket, just one mistake by a batsman is sufficient for the umpire to raise his finger.
In Bangladesh, self-acclaimed as a model for democratic governance, what exactly is the measure of the 'Shame Index' before a public representative voluntarily resigns, since there seems to be no criteria set by the upper echelons in authority, to ease him/her out of office even to save their own face? How many 'emartis' (traditional sweets) must the somersaulting senior-most minister swallow before signing on the dotted line and sparing all of us from further indignity?