The Chicago Manual of Style says
A phrase that is restrictive—that is, essential to the meaning (and often the identity) of the noun it belongs to—should not be set off by commas.
What sort of phrases cannot be restrictive or non-restrictive? What about the following, is 'rusted' non-restrictive?
- Your car, rusted, looks ugly
I don't think so, because it seems to me to change the meaning of the predicate, that your car looks ugly as it is rusted. Why is the sentence not grammatical?