How not to collect data

Would you give your personal details to someone without knowing what they're going to be used for? How about if I said, "give me your name, email address and post code" and I'll make you a member of our exclusive most-favoured customer club? But, I'm not going to tell you what the terms and conditions are, how I'll use the data or even who I am except by vague implication in the latter case?

How about if I wrote the above on a piece of paper and left it on an official looking stand in a shop...yes?

Seen in a shop in Finland:

The text says:

Join now as a favoured customer and you'll hear always as the first about our fantastic offers and wonderful happenings. 

If you want to join as our favoured customer just fill this form with the needed information and hand it to the staff and we will take care of the rest. 

Name:_____________________________________________________
Email:_____________________________________________________
Postcode:___________________________________________________

I tried asking the store staff but they say it is a different company's problem and they have no idea of how the forms will be used. So far I've had no luck in contacting the company to which the forms probably belong...