The commutative property of double negatives

Those of us who paid attention in school (at least periodically) will recall that, in English at least, double negatives are a bad thing. They cancel each other out; as a result you often end up saying the opposite of what you mean to say. For example, if one were to say "I didn't say nothing", that might be interpreted as meaning that I did in fact say something.

For your edification, I submit the following question: does the same sort of principle apply to other restrictive declarations? This morning I saw a sign that read:

"Faux imitation leather chairs"

Do "faux" and "imitation" cancel each other out? Is this chair really made with good ol' cowhide? Or does "faux" actually intensify the imitationiness, i.e. this is not even imitation leather, but some crude knock-off of imitation leather?

To really have some fun, let's throw another spanner into the works:

"Genuine faux imitation leather chairs"

And people wonder why machine translation still hasn't become a reality...