My alliance has a "no first use" policy. That means you don't spend any cards or gold at all, until there is clear evidence that another player is using more than a "normal" amount of gold. We don't really care about the small spenders, dropping some extra resources or a unit or two; but when it gets more, we try to gauge how much they spend, and then retaliate in kind.
Player etiquette has changed a lot since the new generation of players stepped in who aren't really interested in a balanced and fair game (like Bytro wants them to), and dropping cards isn't considered "bad etiquette" anymore (when you confront players they respond "what is so bad about it", and you have to have a good and long talk with them), but it still works as a general guideline of personal ethics.
The good thing about it is, of course, that when you don't use many cards but you DO earn them, when you meet one of the really vicious whales, you have a large stockpile to make them regret the day they chose to spend money.
