I have been following Scott Sumner's blog, The Money Illusion, intermittently pretty much since he started writing it. I mentioned him here and here back in 2009.
I was ecstatic when he joined EconLog, along with regulars Bryan Caplan and former student David Henderson. His insights and his energy contribute to making EconLog one of my favourite blogs.
His recent posts about how the Keynesians [typically of the Alvin Hansen type: spend big and forget about the deficits] had it all wrong are persistent in demonstrating how awfully incorrect the Keynesians have been. This one from a couple of days ago says it all best, I think, with his criticism of the Congressional Budget Office's forecasts using what are basically Keynesian models. His concluding remarks:
Two grand Keynesian experiments and two abject failures. Followed by two times where the Keynesians started crowing about how they'd been right about everything. You can't make this stuff up.
PS. Some people ask me; "If the Keynesian model is so bad then why do experts like the CBO use that model?" Good question.
To see his explanations in detail, follow the link. It's clear and careful.
And what the Keynesian models invariable miss or mis-estimate is the importance of money, monetary policy, and central bank behaviour.