Probably "fake" is not always the right word. Many items I saw on Ebay are not really fakes. It is more question of age and quality.
It is no problem to take a "new" statue, digg them in the sand for a week, pour some water on it, let the sun heat the sand - and after quite short time it will look old.
But most vendors on Ebay don´t say its old, it´s just what you believe seeing it. Thats one trick, make them look older.
The other trick is to take worst mass production and make a nice pic. You don´t say its old

, you just add a sentence saying your grandfather brought it with him from Africa (whenever this happened ...).