We've got more than a couple of softwares that promises - and delivers - amazing image editing capabilities for the average user. More than just pimples and red eyes effects removal, it offers the editor the possibility to change just about anything.
Aside from the obvious leisure uses, it also has a play on more serious issues. And that's older than you'd imagine. A known case is that of Lenin picture. Stalin, after taking over the Soviet Union, eliminated all traces of his political rival, Trotsky, from the official pictures with Lenin. That, according to historians, was a measure to distance him from the people. It can be seen below:
On this fairly old scenario wherein what you see doesn't always pass for truth, images should have less value on the trust department. On this case, because they can be closely inspected for discrepancies, words by themselves would be much more reliable. One could object that images can be investigated too, however, as seen on the sample images, even techniques that are more that half a century old leaves little to no clues.
Therefore, an individual, when reading, has his own mind at a state of absolute attention, ready to idetify mistakes, be them deliberate or unintentional. Unlike when this same person is just glancing through an image among many others, with his/her mind set for automatic swalloing of anything thrown at them.