The slurred words may have been what got him into trouble, but the grumpiness, negativity and evasive non-answers were all just par for the course.
That's why Fianna Fail's attempts to spin this as an issue of style rather than substance is doomed to failure. The real problem as far as the public is concerned is that this Taoiseach is not providing either.
Yesterday's performance was a tipping point that encapsulated all his faults into 13 minutes of car-crash radio -- and if it doesn't convince FF TDs that they need to find themselves a new leader fast, it's hard to see what will.
To be fair to the Taoiseach and his colleagues, they did a pretty good job yesterday of circling the wagons and putting up a united front.
In particular, Mary Hanafin and Micheal Martin (who would both be potential leadership candidates if a vacancy were to arise) could not have been more steadfast in their defence.
Whether or not Cowen deserves it, he seems to inspire a loyalty from his cabinet ministers that many other FF leaders would have killed for. Even so, the FF spin that this has all been whipped up by an orchestrated Fine Gael hate campaign just will not stand up to scrutiny.
Well before Simon Coveney had posted that infamous tweet claiming the Taoiseach sounded "halfway between drunk and hungover", radio programmes were being inundated with even less flattering comments from irate listeners.
Many of them had already been up for hours, packing kids off to school and rushing to the office -- and for obvious reasons, they were none too impressed by the sound of a Taoiseach who had apparently just rolled out of bed at 8.45am on a Tuesday morning and hadn't even had his breakfast yet.
During his robust press conference later that afternoon, it became embarrassingly clear that Cowen didn't know what Twitter was. Sadly, this ignorance of 21st century technology goes to the root of all his problems.
The Taoiseach has never really grasped that in modern politics, half the job is about communicating with the public -- something that Bertie Ahern, for all his faults, understood.
No matter how hard FF try to dismiss this controversy, the bottom line is that Cowen was knocking back pints, doing Micheal O Muircheartaigh impressions and belting out Paul Brady songs just five hours before he was due to address half a million people.
At best, that's unprofessional. At worst, it suggests that he has no idea just how important such media opportunities are -- and if he hasn't learned by now, the chances are that he never will.
It is significant of course that because it was a FF event rather than a Government event, the Taoiseach was in Galway without Government Press Secretary Eoin O Neachtain, whose salary is funded by the taxpayer.
So what should the consequences be? That all depends on FF TDs, who arrived at their Galway think-in feeling gloomy and must have left for home in the depths of depression. Their dilemma seems to be that while most of them realise they are doomed under Cowen's leadership, they like the man personally and have no desire to see him humiliated.
The events of the last week, however, should persuade FF that this kind of sentimentality is a luxury they can't afford. Since last Wednesday we've had the announcement of an Anglo Irish wind down without a final figure, the Freefall documentary that exposed the Government's role in the banking crisis and Brian Lenihan's warning that December's Budget will be even more savage than expected. The country is now in a war to preserve our economic sovereignty -- and instead of a Winston Churchill, we seem to be led by a less articulate version of George W Bush.
Brian Cowen has let himself and the country down. He will not recover from this -- and the only question left is whether his FF colleagues will have the guts to remove him before the voters get their chance.