wcj,
That will depend on your application . Of course, being in the youth flying club before, having a PPL etc will show. That's just the application alone. Questions, i believe they do ask questions like " What was your last flight? to where? at what altitude it was flying at?" what make the plane was, what was the distance and all. Your interests also plays a vital role when they ask about you. Do not exaggerate about your interest for flying because they can tell if it's a cock and bull story. As they say, empty vessels make the most noise. Don't show you are too smart about your technical knowledge when you don't have any flight experience at all. As they know it's all learnt and memorised. If there is real interest, you would have done something about the interest when you were younger or such. So it's not easy to try to bull**** your way through.
Another point to note is your interest in the industry... what's happening in SIA and such. A person who is really into flying would know the industry in and out, have opinions and keep up with the lastest in SIA and around the world. But that will be for the tea party talk. That's where they judge your interest also. All these are things which you can't learn overnight. It takes time. Always be prepared in advance.