She's hyper, can't stay still for any length of time, and always has to check something out. Then she'll stop and fixate on something for a while and dash off again. From a standing position she can jump up almost 1 m high. Her tail and butt wiggle non-stop if she thinks you've got something for her and she's always 'smiling'. Always have to keep an eye on her, otherwise you're liable to get smacked in the face by her snout or clobbered with her tail.
But you'll never see it if you're not part of her trusted circle. Getting there isn't hard, but takes some patience. Food helps a lot with this but it needs a lot of patience.
I think it must be the sight hound part of her. Looking at her, I see more whippet/greyhound than lab. A fat hairy whippet (not that she's fat or anything) is what she makes me think of. She definitely has the food drive of a lab though.
Mel's a pretty good dog, but she needs some work before she'll be ready to go to a forever home. Definitely needs more obedience training to reinforce what she knows. She'll be the dominant dog given the opportunity. Don't be fooled into thinking she's trying to be cute when she puts her paw up on you or nudges her head underneath your hand for some petting. That's just her trying to manipulate you.
If I can get her more people-socialized and past her fear/nervousness issues I think she'll make a great dog for someone. I have a feeling she might do well with agility work.