Answer:
I start new then become old. Start clean but become dirty. I usually start big then become little. What am I?
What is it called when a cat wins a dog show?
I am a portal to another world which you cannot enter. Only you can see me but I can't see you.
Some will use me, others not. Some have remembered, others forgot. For profit or gain, I'm used expertly. I can't be picked off the ground or tossed into the sea. What am I?
You cannot keep me until you have given me. What am I?
Whoever made me don't want me. Whoever bought me don't need me. Whoever use me don't know me.