Cashing cheques locally results in the lender being unable to look at a financial 'trail' for want of a better word of your incomings, outgoings and other financial commitments. This in turn affects your credit rating.
However unpaids suggest you lodge some money to your bank account? Obviously if the money isn't in your account and cheques/direct debits bounce, this also affects your credit.
In your favour you can provide evidence of savings, payslips etc and you have equity in your home.