Many dogs love sugar, but shouldn't have it. It's extremely bad for their teeth and you sure don't want a huge vet bill for dental work on your dog.
Yes, many breeds of dogs actually have a sweet tooth just like humans and once you give them anything sweet some may sneak it or at least expect more. Of course chocolate is deadly for dogs. If your dog sneaks chocolate take them to the vets immediately and the vet will give a charcoal formula to absorb the chocolate; make them sick and also have bowel movements.