This wing has a footprint from white paint. I have never seen a dirty airplane wing and I have seen a lot. This is strange, most airplane wing are spotless, and shinny like stainless steel. This one also had rusty bolts.
This is the only airline that flies presently between Bali and East Timor.
I recently had a flight with an airline with truly rusty wings. I found your post while Googeling for similar stories from others. Its amazing how vulnerable a ugly looking plane can make you feel.