Lol, what's so hard about saying no? No-one's going to badger you asking you why you don't have one, throwing the form in your face.
We have to ask. If you're on tills for hours and you forget to ask one person, that person will always produce the card when the sale is done and go absolutely mental. One reduced a girl I work with to tears one day. The sale will always be small and mean they've lost out on a whole 10 points or something, ughh. People do moan about this to head office too. I don't ask people who look like they're tourists/people who look too young to care about having one and in general, men, unless there's a wife somewhere.
Also- you're not supposed to exchange valueclub vouchers for gift cards, obviously it goes on but I've never been asked to do it, or seen anyone being asked to.