http://about-france.com/french/articles.htm describes when to omit the article.
► In some fixed expressions, singular nouns can be used without an article. But note that this is exceptional. ► The article is normally omitted when indicating a person's job. ► It is also normally omitted in generalising cases after de: this includes cases following quantifiers such as beaucoup de (lots of), peu de (few), trop de (too much / many), etc.
It's not garçon mauvais because the sentence doesn't call for a criminally bad boy. See northern guy's explanation at http://www.duolingo.com/comment/175977 ('Les hommes mauvais')
In french, there's a group of adjectives that naturally precedes nouns. You can remember them using the BAGS acronym. See http://french.about.com/od/grammar/a/adjectives_4.htm
Okay, would anybody explain to a supposedly stoopid (read: supposedly unable to learn any language beyond English) person such as myself why is it that sometimes there's such discrepancy about the presence or absence of an article in some of the sentences between English and French?
the sad fact of the matter is that languages are not logical; we say things the way we do because that's how we learned them from our ancestors, and many details change from one language to another. So it can be - yes - frustrating (and it requires a lot memorizing of all these itty-bitty rules).
rfi.com is a security company. Do a search for rfi + easy french. It will get you there.
I don't know how easy the broadcast French was because I wasn't able to understand any of it. If you are a news junkie like me and know what's going on, the little written tests at the end of each broadcast were doable.(and interesting) They have games and stories etc. which presumably were easier than than their broadcast material.