Here's a quote, paraphrased, from Jeffrey Sachs, known economist "the signs were all there for the housing and credit bubble, so why didn't us in the field see it?"
It's a good question, I think the answer is because economics isn't focusing on the actual economy, or rather the financial economy (all we care about anyway). It's focused on a bunch of stupid numbers, or maybe practical solutions to smaller problems.
At the same time, I've heard and read of economists saying some amazing true things.
And personally I wouldn't know what to tell you, because economics and common sense are completely mixed up, I don't know where my thinking starts being economic and ends. Just read and immerse yourself, but be careful too.