The answer to that is going to depend on how bad is bad. The score itself is very important, generally requiring a 620 middle score to get a deal done. But there are particular issues that could totally negate any hope of getting a loan. A foreclosure, for instance, is going to keep you out of the market for at least 3 years. However, if you just have low scores because of not enough credit or balances that are too high then those type of things can generally be improved, sometimes quickly. It's just impossible for anyone to advise you too closely without knowing EXACTLY what the "bad" is.