Be advised: anonymous questions on ask.fm are not fully anonymous. This is a major security glitch.

Elliot Temple
ask.fm has an internal blacklist. If an anonymous question-asker is on the blacklist then your answer doesn't get tweeted out; otherwise it does. This gives you information about whether an asker is on the blacklist or not, which lets you figure out that multiple questions come from the same blacklisted guy (since being blacklisted is uncommon) rather than from new people.