Accidents will happen and if this happens in the crate, the Lab should never be scolded. If a mess occurs, promptly bring the pup outside to finish eliminating and return to clean the mess. Everything in the crate should be cleaned as microscopic particles of urine or feces can be on anything. Any residue or odor left behind will leave a scent or marking for your pup to use next time it needs to eliminate. Therefore, all bedding and the crate floor should be washed with a pet odor neutralizer (such as Nature's Miracle).
The crate doesn't work for all dogs. Some dogs will not tolerate it but most will come to love the crate and be lost without it. Success rates are much higher for puppies, than for "senior" dogs. It is important that the crate not be abused. Every dog needs a certain amount of exercise and should be allowed the opportunity to socialize daily with its human family.