Here's an original cel from Shimai Ijiri (Slave Sisters), a Japanese hentai anime show from the 90's.

Cels are used to create the actual anime and are rare and unique in nature. 

This 2 layer cel is a complete set as it comes with the original, matching background and with douga, the sketch which is used to create the final cel product and also a layout (copy - picture 4).

The cel features Yukari in the second episode (the infamous dream scene).

There is no trace of vinegar syndrome: no smell, no waving. 

There is no sticking to the background, there is no sticking to the sketches.