Remember: body parts can't move on their own.
Her arms flung out to grab him.
His hand rubbed her back.
Her eyes swept across the room to the door.
A person has to DO the action using body parts; they can't DO anything on their own (unless you detach these parts and they have the ability to move on their own).
How many times have you read "wandering body parts" (WBP) sentences without thinking about them? I would guess many times. Your brain knows what the author is trying to say, and you just accept "moving parts"!
I know that when I judge contest entries, I'm more aware of WBP...maybe because I'm reading with a different sense of WHY I'm reading. For books I choose to read, I may skip over WBP a number of times. But if it becomes clear that the hero/heroine have lots of disembodied parts moving all over the place, I usually take note and will either finish reading the book realizing this or decide to stop reading.
Do you have any WBP encounters to share? Have you (authors) been guilty of this?
photos:Flickr: Chris Piascik's photostream