To answer your question. Is it bad to spoil her ?
Truly that depends on her personality. If she starts guarding behavior with you (growling at other people) I would be worried. My 8 yr old Rubin is spoiled but I draw the line at him growling at people. He is allowed to boss the other dogs but, not people. Gracie is my little rescue and she is spoiled too. But I have to remind her every day she is not the only Yorkie I love. I often give in to her begging behavior to be held or for treats (I know ! Trainers should have perfectly behaved dogs. But my Yorkies are ... you know my Yorkies. Now back to yours..
) You are the PLP in your family (PLP means protector,leader, provider), So you make the rules. If she is a terrific companion, obeys when you need her too, and is well behaved, don't worry. Some Yorkies make perfect shadows and are well balanced happy dogs.