If you buy from a reputable breeder, they will know which bunnies are healthy and which are not. If they are a good breeder, they will NOT prompt you to buy an unhealthy rabbit. We DO NOT sell any unhealthy rabbits from our rabbitry, ever.
Still, here's the signs of a perky, healthy, Holland Lop bunny:
EYES: The eyes are wide, attentive, alert, dry, and follow your movements. The eyes are not crusty, red, or watery.
NOSE: The nose is twitching and dry.
EARS: The ears are scentless, clean, and the bunny is not constantly itching the ears.
PAWS: The paws are not crusty, which is a sign the bunny has been wiping its nose. Yellowness from the urine is fine, and completely normal.
BUTT: The bottom is clean, not smelly or stinky. Unspayed/unneutered does/bucks may emit a smell from the scent glands down there, but it's not usual. If a rabbit has a smell like this, spaying or neutering usually eliminates the odor.
MOVEMENTS: The bunny is moving normally, hopping, inquisitive about his surroundings and comes up to you when you open the cage door (unless the bunny is just shy). The rabbit takes interest in its food and eats fervently, as well as drinking normally and often.
FUR: The fur lies down nicely, isn't matted, and isn't dull or in a constant molt.
TEETH: The top teeth slightly overlap the bottom. It's considered malocclusion if the teeth are in any other position. Bunny teeth generally stay in the proper position. Malocclusion is usually caused by poor breeding because it is hereditary, but it can also be caused by a rabbit chewing on the cage bars or falling and hitting it's face.