Why should I not use standard "house" bricks for a patio?
My wife and I collected an assortment of old house wall bricks from various sources on craigs list and put them down in a patio in the mid-Atlantic a couple years ago. They're on packed gravel and sand with no mortar, laid flat in a herring bone pattern. We've had only one issue which is that some of the bricks were of the softer, less dense variety (light orange and easy to cut). These didn't make it through the first winter. They seemed to have trapped moisture, froze, then exploded into very small pieces. We'll be pulling these out and replacing them. 

Other than that we found the old bricks to be great. Patina and slight variation in size make the patio look older than it is. Lots of character and other than a few exploding bricks, little maintenance.