I don't believe that a gray goo recipe can look like a cake recipe. I believe there are recipes for disastrously harmful things that look like recipes for desirable things; but is a goal-less Question Answerer producing a deceitful recipe more likely than a human working alone accidentally producing one?

The problem of making the average user as prudent as a Less Wrong user seems much easier than FAI. Average users already know to take the results of Wolfram Alpha and Google with a grain of salt. People working on synthetic organisms and nuclear radiation already know to take precautions when doing anything for the first time.