It must be the way you answer them. Interviewers sometimes ask stupid questions. They mostly want to see how you answer and see where your mindset goes. I believe you have always been giving them a hack care impression, ie. I am not that interested in the post and can do without this job. If you attended 10 interviews and can't get a job, reflect upon yourself, where you have gone wrong, instead of cracking your head thinking how to create a fool proof lie. It doesn't work. They are not stupid.