When i was in the cellular industry, specifically
Post# of 8802
Since "bad debt" is is a loss that you cant get back, it is most likely chargebacks that you see on the "bad debt" income report. It seems to vary from year to year, but is still high. The higher the revenues go, the higher that will most likely be.
Im not 100% sure if that is the case, but I couldnt find anywhere else where chargebacks would be in the loss column besides the "bad debt" section. Technically it isnt even a loss to the master dealer, but it is able to be written off, and you can bet they are writing that loss off for tax purposes.