Survey answers when you ask people to state the obvious

You run a survey and you ask two questions which should have fairly straightforward answers: 

Question 1: Are you Male / Female?

Question 2: What Colour is this?

The following comic from doghouse diaries, and the results of an actual colour survey at xkcd tells you a little about the validity of surveys...

 

The write-up about the "male / female" categories and the controls they tried to implement for color blindness at the xkcd blog is also something worth reading.