I hate to be ungreatful too because it is the thought that counts but seriously you sit and wonder sometimes.
My MIL bought me a pair of size small pajama's the first year dh and i met (when I am very clearly not a size small -- she is smaller than me and wears a medium duh) in his family before they got divorced they used to have a tradition of the girls wearing pajamas all day on xmas and the guys would do the cooking and cleaning well so infront of everyone she tells me to go put them on and had to explain to her she got the wrong size. Her response to me was oh well then i guess next time you shouldn't be so shy to share your size and this wouldn't have happened.
Also one time when I was 12 or 13 my grandma got me a windchime that you'd put on your porch LAMO.