qdbus can connect to either the system or the session bus depending on the --system parameter.

However, accessibility, for example, uses it's own bus that's independent of those two.

The dbus-monitor tool provides an --address parameter to manually specify the bus address for such an occasion but qdbus doesn't.

Because I needed to browse the accessibility bus I added the same parameter to qdbus as well.
I attached my tiny patch to this bug report.

Maybe something similar could be integrated?