haha, ours is wrong too I think, but when going to the doctor keeps me honest =)
If you guys are looking for accurate scales for your pups, at the hospital we use human baby scales for smaller dogs that work very well. Human home scales normally require a minimum weight or pressure in correct areas to meausre correctly, so unless you are doing the (weight of you+chihuahua)-(weight of you)=weight of chihuahua, it may not be accurate at all.