Here's an interesting one... I've had some issues with a USB Gamepad device appearing on my MD (HP 6710b Compaq notebook).
I didn't even notice the device being added until it caused problems - It got into a loop at one stage and just kept adding devices and, then when I wanted to configure a Wiimote it caused havoc with that - they don't like to co-exist, it seems.
Anyway, the issue seems to be the following-
The detect scripts for the USB Gamepad device check for, among other things, a joystick device- ie the existence of a file /dev/input/js0.
Well, in my case, that file is created by the X configuration because the configuration detects an internal accelerometer in the notebook (apparently it is there to protect the harddrive or something... not sure how, maybe it yells "CATCH MEEEEEE" over the PC speaker if it thinks it's falling or something) and sets it up as a joystick device. Jeepers, so I suppose you could play games by flinging the notebook around. Anyway, the point is, that sets up the /dev/input/js0 device which then triggers the USB Gamepad device creation.
At the moment I'm testing a bazooka-hack to stop this but we'll probably have to look at a cleaner method. Will report back...
(II) config/udev: Adding input device ST LIS3LV02DL Accelerometer (/dev/input/js0)