I just had a rather unpleasant experience that I'd like to share with you.
Through a image-sharing site I'm a member of (where I put the stuff that does not fit here) I got contacted about some images of the "Spirit of Ecstacy" (the winged woman on the hood of classic Rolls Royce cars) I'd taken.
The guy wanted to know if I was ok to license the image for the internal magazine of a company that does some testing for parts of the car, but that there was no money involved (basically, "can I have your image for free").
Now, I do not give images for free, unless it's for a non-profit organization, so I asked for more details about the company and the magazine.
Turns out, the guy works for a design agency that was contracted by this multinational, equity-owned, company to design their internal magazine, and quite obviously there's quite a bit of money exchanging hands.
So beware, because things are never quite what they appear to be on the surface...