A: Sure they can, if they eat the wrong things, or catch a stomach virus.
However, there's usually not so much of it. And they generally keep it in their cage.
They usually don't spray it all over the walls.
And they usually don't write with it.
It would be unusual for a bearded dragon to write "Worst Roommate Ever!" on my door.
You see, bearded dragons can't even read, let alone write, let alone compose a sentence. An exclamation point would be a complete mystery to them.
Is there something you want to say about our living situation?