Saw a TV program where they went through the rubbish that high street banks leave out on the street waiting to be picked up. It was full of confidential details bank numbers all sorts It wasn't shredded or anything. They even phoned up some of the people who's details were found live on TV to see what they thought of it.
After the prog they informed the banks and a couple of weeks later they went back to check up whether the banks were disposing of confidential waste securly and many were still just chucking this stuff out with the regular rubbish!
Its a lottery whether your details get picked up or not, no matter how careful you are.