I think there is a difference, though, between prefixes and suffixes in that the former don't usually change the grammatical category of the word they're affixed to (adj. "clear", adj. "unclear"; vb "consider", vb "reconsider"), while suffixes often do. This distinction would be relevant to Salad Dressing's question in that they also ask whether one can turn any noun into an adjective. One can do so with many nouns by adding a suffix ("hope", "hopeful"; "love", "loveable"; "sun", "sunny"), but I couldn't say whether just any noun can be turned into an adjective this way.