In an effort to combat forum spam, I’m experimenting with challenge questions. It’s an interesting problem with a seemingly infinite amount of options. The typical 2+2 = ? is too easy for the bots, as are most math problems. Word problems, especially ones that are relevant to the forum are proving more effective. This may be for a number of reasons, not the least of which is that the questions are in English and the bots coming out of China don’t know what they mean (any more than I can understand the simplest of Chinese characters).
Then there’s the logic behind the question. This can be set very high or low. Set to an extreme, you can be sure that only a handful of people would know the answer, for example, who attended a private event. Other techniques, such as using various forms of cryptology to scramble or obfuscate the questions, is another direction an admin could go to weed out the bots.