The first was malfeasance by not doing due diligence by the Irish banks and the foreign financial institutions who lent money to the Irish banks to fund the real estate bubble.

The second was the improper action by entities in the Irish government who bailed-out the Irish banks and loaning foreign institutions.  Proper financial regulation and oversight would have would never allowed the Irish banks to get into this mess in the first place; proper financial regulation and oversight post-mess would have let the banks fail with the Irish government "picking-up the pieces" as Migeru has already outlined elsewhere in this discussion.

Debt is paid off by the cash stream generated from the productive (goods and services) assets the debt was used to purchase XOR the cash stream generated by a vibrant economy and then redirected to debt service.  Consumer real estate purchase is a perfect example of the latter.  (At least as long as the house, whatever, is held by a consumer.  I note purchase for rental is different.)  Consumer real estate does not generate cash but, rather, is a net drain of cash when viewed from the total amount of discretionary consumer income.  This means:

As the cash stream generated by the Real Economy is diverted to debt service the total amount of consumer spending MUST fall by that amount.  This, in turn, lowers economic activity (eventually) in exactly the place where the cash comes from to service the debt: the "Real Economy" where people create wealth by producing goods and services and get cash for so doing.

The result of this has been analyzed (no link, for which I apologize) to conclude banks and other financial institutions withdraw, roughly, 7 pounds for every pound of debt issued.  No economy in the world, including the global economy, can withstand that rate of predation.  Eventually marginal borrowers will be forced into non-performance initiating a positive feedback loop in the negative direction and the bubble bursts.  

No one 'round here, I should think, is saying debt is necessarily evil.  Debt assumption for increasing production generating an Internal Rate of Return (IRR) (cash) capable of debt service is a vital part of a non-barter economy.  Debt assumption that doesn't generate an IRR and simultaneously reduces the ability of the micro-economy to service that debt is stupid because it WILL, eventually, crash the economy.  

As a former banker, I can tell you there are known methods and procedures for determining the credit-worthiness of borrowers.  Running those is what Due Diligence is.  Since 2004 I have been warning the ever-increasing amount of money flowing into real estate was going to crash the global economy because I ran those methods and procedures.  The various financial institutions did NOT go through that process and, IMHO, should be held accountable.  

Ever since I learnt about confirmation bias I've started seeing it everywhere