In all honesty from what i have seen it's the simplest ones that do not take much thought.
smart questions or interesting ones
ones by popular people, and i suppose ones that apply to most people
from experience, (cough) it's 2 things.
1. be sexist . eg: are women just smarter than men?
2. have tokens to extend the life of said question
that's just a primer, adding a touch of wit and irony will also add to the longevity.
probably the ones about God, or politics
Provocative questions. Answered by troll feeders.
The non-sexual ones with wit and IQ.