This helps me a lot. With the Amazon, I could always tell what he was up to by his body language. Even the foot up, bait and bite manoever was transparent by the look in the eye and the feathers slicked. But Gus, the B&G, has been a puzzle. It's reassuring to hear they are all like this. It's just like Birdman666 says - poofy head feathers mean scratch here or bite time or get away from the play top. The other day he got me. He was on his perch and had been hollering to get out, so I opened his door and reached in for him like I always do, and he lunged at me so I stepped back and asked if he wanted out. He looked poofy and excited, but held his foot out, so I went back for him. Saw the beak come down, stayed where I was, he grabbed on pretty fiercely but then stepped up at the same time. I said ow, don't bite, finished bringing him out of the cage and put him on his outside perch. He didn't break the skin, but I had a red beak print on my wrist that lasted several hours.
I'm not sure how to interpret it...did the foot up mean he wanted out, but he wanted his person - who was in the room - to pick him up instead of me? Or was he just so excited that he was of two minds, yes pick me up oh I bite you? I guess the lesson is that an excited macaw is unpredictable and probably has poor impulse control, so don't put a body part near unless we are both calm. He's a LOT harder to read than an Amazon.