In the US at least, airline frequent flier miles are the center of marketing efforts for credit cards, hotels, car rental and even restaurants. One of the big marketing campaigns for a credit card mileage program is 'what's in your wallet?' - maybe a credit card accumulating miles with no blackout dates. Since airlines frequent flier programs have become renowned for making it almost impossible to get the free tickets you feel you are entitled to, when you want to use them, does this put people off actually trying to use their miles?
Try this short (one question) online survey to show how you use your miles, and see how you compare with hundreds of other respondents. Interestingly, there is no link back to the sponsoring website (Cheapflights) and nothing asking you to identify yourself. There is no fear of spam, so these guys are relying on word of mouth and good follow up PR to gain any benefit from this survey.
I was happy to do this survey, because it gave me some instant feedback. How many surveys are put out to solicit customer feedback, leaving the customer feeling unrewarded with a 'thanks for your time' but no other feedback. Just seeing the current rating on how I voted alongside everyone else gives a feeling of interactive satisfaction.
Now, I wish it was that easy for me as a product manager to get hundreds of data points to feed into product decisions and better marketing!