O.K. I've read the thread but it has not answered my question, or I'm too thick to follow the thread, but - I uploaded a straight forward image of my dog. The file name was Dobie X.jpg.
When I searched for that file I found it and downloaded it. And all I got was an advert for iPods!
Now, I have nothing to do with spam and I know nothing about iPods, so how did the image get changed?