Well, this is a good news bad news sort of thing I think. If it's true that American banks are declining mortgages to all but the the extreme upper end of credit scores then providing them assurances is a good thing.
People make mistakes, and if you've ruined your credit rating it can take a long time to improve it, regardless of how much you've changed your circumstances and philosophy about debt, borrowing and fiscal responsibility.
To my mind, if you can demonstrate adequate income, take the steps necessary to recover your rating to a certain point thereby demonstrating that you have learned from your mistakes and become a more responsible adult, and can provide a minimum of 10% down, you ought to be cut a little slack.