You can train them, but your expectations for a lizard are a little high. It's probably like training cats -- the result is that the owner gets trained, not the other way around.
If you spend a lot of time with your pet, you should start to recognize expressions; like, "I've got to poop," and "Aaah! there's a huge person coming after me!"
One tip is to move slow and try not to approach from blind spots. Then, try to discover the lizards 'personality'. You'll have more luck if you get to know the beardie than if you try to reach a level of understanding.