Answer:
What type of shoes do spies wear?
Though desert men once called me God today men call me mad. For I wag my tail when I am angry. And growl when I am glad.
Can not be bought, Can not be sold, Even if it's made of gold. What is it?
I reach for the sky but clutch to the ground. Sometimes I leave but I am always around.
I am in the past, never in the future. I don't exist, but have existed. I saw what you saw, and this is what I will ever see. What am I?
Whoever made me don't want me. Whoever bought me don't need me. Whoever use me don't know me.