This is a bug that bites my companies bottom line. I found a way to see which sales were not paid. 

go to your QB merchant services account. Search all your sales transaction for the last year it will only go back a year. Then export all the data to a spreadsheet. The transactions that are credit card sales that say "paid" have not been processed. The ones that went through say paid_payment_success. Good luck this happens to us when we don't close out the sales transaction with the process payment box checked