You get what you inspect, not what you expect.
An acquaintance of mine recently told me a story of buying multi-function tools as a branded promotional product. These were going to be given out to current clients of his company. He explained the process they went through to pick out the tool and place the order.
When the custom promo products came in, he was incredibly disappointed by the lack of quality. In his words: "They looked like they were 'used'! They had scratches all over the plastic handles… on top of our logo… and even all over the backs of the blades. They look like they have been jostling around in my car trunk for the past few years!" I asked to see a sample, and sure enough, these were awful.
When he called to complain to the company he bought them from, they told him that they "do these all the time, and have never had a complaint." That's hard to believe… these were nasty. As I mentioned, I saw a sample, and I certainly would refuse to sell them to my clients. In fact, I wouldn't take them for free.
The best way to not be surprised by the quality - or lack thereof - in custom promotional products is to request a pre-production sample of the exact piece you plan to order. It needs to be the exact model… not one that's 'similar.' Make sure you plan far enough in advance to be able to get the sample… you can then be confident that your customers will receive a high-quality piece that reflects your appreciation - and your company brand.