In every barrel there are a few bad apples.  We generally let people behave as they wish to but encourage people to behave honourably. 

We operate a number of schemes to help us weed out those who do not do so however.
Speed traps – if a member completes a survey (or a section of a survey) too fast then they will be issued with a speeding ticket.  Three strikes and you’re out.
Consistency traps – if a member consistently answers “A” to all questions then they get a ticket.  Three strikes and you’re out.
Inconsistency traps – if a member answers inconsistently to all our consistency check questions then they get a ticket.  Three strikes and you’re out.

In addition we are developing a "Truth" algorithm which combines these measures above as well as several others (such as frequency of updates) to create a single measure for how much we trust a specific response.

Finally, all prize draw winners have their past surveys reviewed and if we find evidence of lack of care in completing surveys we believe it is only fair to re-draw the prize and award it to a more deserving member.  We publicise the occasions when this has happened to demonstrate the benefits of being honest.