Yea, it ran, and ran fine, from what I thought. I went from a '75 550SS to my 919, so I didn't know what to expect. I did empty it all out, and will say, I actually have to 'let it warm up' for a minute before I just take off, and it is MMUUCCHH smoother throughout the RPM range. I will give the dead mouse credit, he did travel 1200 miles in filter.
I know exactly what you mean, I opened my airbox on my 05 VFR and found this. The bike was used (barely..5000Miles) and i bought it from a dealer..so I was abit shocked to find that in the airbox, but the ran great even with the filter completely clogged.
I had left my car with my parents for about 9 months while I was out of the US. I got back the blower fan for my AC shook the entire dashboard and sounded like rocks in a blender. I opened the dashboard and inside the squirrel cage fan were acorns and a dog terd!! It ran much better without those in there!