@dave r said:

If there's an raster images or raster/hybrid rendered viewports in your SketchUp model there should be a folder included with the .dwg export. Obviously you would need to send that folder along with the .dwg in order for the .dwg to open correctly.

If the viewports are rendered as Raster, you won't have any vector linework in the .dwg at all.

Thank you, this question was also relevant to me.