You have to be very cautious with shelter pups and see if the shelter can provide as much information on the pup as possible. We adopted a beautiful Siberian Husky, but she was definitely a piece of work. After about a year of training her and sending her to 2 professional training programs, she became the sweetest, most obedient pup-- unless she broke loose from the backyard. Another issue with her was that she missed her socialization phase (we were told by one of the trainers), so she hated other dogs and was very territorial-- as most huskies are. Getting a shelter pup is definitely a loving thing to do, as these pups need a home more than anything, but do your research on the breed you select and try to get as much background info as possible from the shelter or any previous owners-- if possible.