The use of images taken from Flickr is notorious, even large multi national companies have been known to use it to get a free photo for their advertising.  Such as the case of Alison Chang a 15yr old girl who's photo was taken by Virgin and used in their advertising campaigns in Australia. 

Flickr users are given a choice when they upload of how they would like to license their image. Many choose ' common license'  which allows the taking and using of the image by anyone even for commercial purposes.

 

And every one said, 'If we only live,
We too will go to sea in a Sieve,---
To the hills of the Chankly Bore!'
Far and few, far and few, Are the lands where the Jumblies live;
Their heads are green, and their hands are blue, And they went to sea in a Sieve.

Edward Lear
http://www.nonsenselit.org/Lear/ns/jumblies.html