Getting live inventory counts is one of the most crucial aspects of drop shipping, besides the drop shipping itself. Once you have the counts, you need a system to end the listing. With some drop shippers the count to end a listing is at 100, while others it will be at 0. It just depends on historical experience and whether you sell long-tail or quick selling items.
You should also test receive a drop ship order to yourself. See how the product is packaged. Do you get a sales receipt, packing slip, or nothing. What does the FROM part of the shipping label say? Is it a true blind ship where your information is on the from, or does it have the drop shipper’s address? Some write something generic like Shipping Department instead of the drop shipper’s company name and use mailing address of the drop shipper. Do this for the various shipping companies they offer. UPS, FedEx, USPS, etc. The disadvantage with having the drop shipper’s from address on the shipping label is that a savvy buyer can do a search on the from address and you have just lost a customer permanently.
If the drop shipper owns a unique product line, drop shipping then becomes about adding value to the customer. Are you adding value by including more content? Are you offering better service than the other guy? It then becomes a marketing game.
You should also have a system to exclude certain SKUs from the feed due to it having high customer issues, not allowed for sale outside of country, unwieldy dimensions, etc.
Any other thoughts on what should be considered for drop shipping?