Labs are generally very sweet and kind. They only turn "nasty" when they have bad training or are wired wrong, and from what you say it doesn't sound like hes "wired" wrong. I have met plenty of nasty labs, but I kind of think that it was the owners fault, just like i have met other breeds of dogs that were nasty, and it was the owners fault. I agree with Cincy'smom, teach him a command such as gentle (i use easy) that lets him know that he shouldn't snap at the food. I hope things work out for you. Obedience classes work wonders too! By the way, welcome to Pet Talk!!