My guess is that if 100 people bought generators with the intention of returning them if they didn't need them, that 100-x people actually return them, where x is probably around 10 or more... People are lazy, decide why not keep it, etc. Worse case senario you have a customer coming into your store twice.. Maybe on the return trip they buy stuff to repair damages from the storm.. If you have the inventory this isn't a big deal and probably ends up increasing revenue vs. not having them buy in the first place.
The generators have a lot more value to being in stock before or during the storm than after. When I bought mine, I had to drive two hours away to a Lowes, because they were out of stock in my county. If the local Home Depot had one, I would have just bought it there. The person buying and returning it is not only costing them a fraction of the cost (credit card fees each way); but also actual sales.
On the other hand, I think that in general, the relaxed Home Depot returns policy helps them. I often take advantage of the ability to buy multiple sizes of things, extras in case I mess something up, and then when I'm done with a project go back return the excess. If you use a credit card, that is even easier than keeping the receipts, they swipe the card, scan the stuff, and it goes back automatically. I find this easier, because I always have my card; and there is no need to have however many receipts that the items were originally bought with. And for very small stuff that I could conceivably use in the future, there is a decent chance I won't bother returning it anyway.
As a native Floridian, here is what I would do. Buy generator, take it to area that has lost power. Resell it for 2x price. Most people don't take care of there generator until they actually need it. It sits in the garage or basement, until the lubes dry it and the bearings seize.
