I will throw out something more controversial: Stupid questions are fine. Why? Because first off, they will not get upmodded, and be trivially easy to answer, not wasting anyone's time reading through them. Stackoverflow has a fair share of trivial questions, and they just disappear after a few minutes into the "answered" heap, and nobody bothers reading them. Since the search algorithms are decent enough, you never see them again either, or if you do, they are usually really helpful but hard to find ("Where does X store my config files?").
If someone makes the effort of actually registering / logging in, then typing out a few sentences with his question, he has spent multiple minutes. Any sane person would not do that without trying google translate first. Put a google translate link visibly on the "ask a question" page.
Anything that goes through the implicit Filter Of Laziness is probably acceptable to begin with. Adding a elitist layer on top of that only results in a specialized page that only 126 people [that's the current rep200+ count as of this writing] use.
"You have to draw the line at some point". The line draws itself. People are too lazy to type questions which google translate can answer.