There doesn't seem to be a clear cut yes or no based on their terms of service from google.
http://sketchup.google.com/intl/en/3dwh/tos.html Base on the people who talked about in the forums
here ,
here &
here I would be inclined to say no for the users ones unless you contact them directly. But I won't claim to really understand there TOS. Archived3D doesn't seem to say anything so those could just be "acquired" from other sites or other people.
I usually stick with
turbosquid or
3docean if I need to be 100% sure. or just make the model myself if I can & have the time.
Greg
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