On some products, like a Lexmark P450 photo printer, I tried four or five USB adapters that weren't recognized by the printer, including one that was on the manufacturer's recommended list. It was using a different firmware version, I guess. But I shouldn't have to guess, and neither should your users.
The third problem with Bluetooth has to do with Microsoft Corp.'s miserable support for it that comes with XP. And the picture isn't much brighter when you move into Mac OS and Linux. Many of the laptop makers have substituted support software from Widcomm/Broadcom or others because the built-in stack from Microsoft does so little and supports so few Bluetooth products.
So an obvious step here is to carefully test the various stacks and settle on one that you can deploy corporatewide. Some stacks come with USB dongles, so again, standardizing on the right combination can really help reduce your support burden. But it isn't something you can predict, and you will have to experiment with various combinations of stacks, dongles and Bluetooth devices until you find the right mix.
In many respects, the state of Bluetooth today is akin to where Ethernet was back in 1990, or Wi-Fi around 1992: a series of incompatible technologies, poorly adopted protocols, and different implementations that will conflict with each other when more than one thing is installed on the same PC.
I don't want to paint all Bluetooth products with the same dark brush - there are some great products out there. I just don't want to have to re-image my drive when I want to switch between them.