So basically the litter had ringworm? Yeah if they are all clear I wouldn't be worried about it, specially since the breeder has been honest with you. I would go ahead and visit the pups. Ringworm can happen to even the best of breeders. One of my litters got it when they were staying with the co breeder, because a stray cat with ringworm shed it in her yard and the mom transferred it to the pups. They were given the best of care to get rid of the fungus, and all got great homes.