Why is isolation a key to success ?
Here is an example: Lets say i'm a buyer and I need a picture with cash for my new "increasing wages" article. I will write this article on a white background (as most do) so I will choose a good picture such as:
All of the above are good examples of isolated images. White background is important since most articles are written on white then you get your picture integrated perfectly. Now find for yourself a bunch of non-isolated images... try to make a difference.