Really you can just always guess. When you can't eliminate any answers, guessing has the same expected value as leaving the question blank. If you can eliminate one or more answers, the expected value is higher for guessing than for leaving the question blank. So in no situations does guessing decrease your expected value.
Test questions like the SAT are designed to have wrong answers that look like they are right at first glance, so people who think they have a better than average chance by guessing often don't because they were baited by one of the wrong answers without thinking it all the way through.