Had to have a look. :)
This is a pretty good study. The word translated "guest rooom" here is:
kataluma
Thayer Definition:
1) an inn, lodging place
2) an eating room, dining room
But look at Luke 10:34 and the story of the good Samaritan:
Luk 10:34 So he went to him and bandaged his wounds, pouring on oil and wine; and he set him on his own animal, brought him to an inn, and took care of him.
In this case the word translated "inn" is:
pandocheion
Thayer Definition:
1) an inn, a public house for the reception of strangers
So there's a difference between a private place for guests and public place for guests. I had always assumed that that the "Inn" that Mary and Joseph was turned out of was public.
It makes much more sense that they stayed in someone's home in the "animal" part and not outside in a barn as is often suggested.
Had to have a look. :)