If one partner in a couple has bad credit, it can significantly lower the chances for the common loan or mortgage approval. In this scenario, both spouses or partners are listed as co-applicants on the loan or mortgage. Hence both incomes and credit histories are taken into account. So if one of the partners has bad credit and also a lower income, it might be wiser and more advantageous to apply for the loan or mortgage only for the partner with good credit and positive credit history.
If you see that both of your credits and incomes do not look good on an application, you can also consider asking your parent or a good friend to act as a cosigner and so a guarantor for your loan or mortgage. The third party can hence offset the poor credit on the common application.