"Rudolph the Red-Nosed Reindeer" TV Special ?

I've always wondered why the "Dolly For Sue" doll is a misfit. I've read the Wiki explanation about the doll suffering from psychological problems causing her to be a misfit but I don't believe that. There must be a physical reason. Does anyone know why the doll is a misfit? Please answer only if you've seen the show. I posted this question last year and one person responded by saying the doll was a misfit because she had only one arm (!).