[Alex Jenyon]

"Ambiguous space" shots are pretty rare. The only real use for them that I can think of is to show disorientation when a character is drugged / knocked out, or in a surreal dream sequence. Neither of which is particularly common in film as a whole, and even fewer would require matte paintings.

Probably best to avoid doing them, since they could very well be confused with unsuccessful matte paintings, even if you did it on purpose.