`If Looks Could Kill" is one of those zany capers that come along occasionally to remind us of the pleasures of Wretched Excess. The movie tells a bizarre story about middle Americans trapped inside the byzantine intrigues of Europe, and is perhaps the only film I can recall in which a mad economist traps an entire Detroit high school French class in an iron cage suspended above a cauldron of boiling gold. At first, it appears the movie is only going to be another one of those brain-damaged caper ripoffs in which boring people do stupid things at half the pace of real life. Then it turns on the supercharger and transforms itself into the kind of hallucinatory fable in which a tiny woman wears a golden whip around her neck, and uses it to reduce foreign ministers into lumps of placation.