I just revisited the QB Help file. Here's how they suggest recording Bad Debt in QB:
From the Customers menu, choose Receive Payments .
In the Receive Payments window select the name of the customer from whom you incurred the bad debt.
Leave the amount field at 0.00.
In the list of outstanding invoices or statement charges, put a checkmark in front of the line that will not be paid. You'll get the following warning: "You cannot apply an amount greater than the total payment plus any existing credits." Click OK. The checkmark disappears leaving a square box in front of the line that will not be paid.
In the Receive Payments window, click the Set Discount button. In the Discount and Credits window, enter the amount of the bad debt in the Amount of Discount field and the name of your bad debt expense account in the Discount Account field.
Click Done in the Discount and Credits window.
The procedure described above does not affect your sales tax liability.
In the Receive Payments window, save the bad debt transaction.
If necessary, change your sales tax liability
I have tested it and it does work.