Here is one recent example of a misplaced picture that can be considered as a hoax.
Link to the tweet (269 re-tweets at the time of writing). Another example (874 re-tweets at the time of writing).
This picture can be traced back to year 2003. Example: Scenes from the Gaza Strip (boston.com). Image credit: MAHMUD HAMS/AFP/Getty Images. See also: TinEye search results.
Why do some people – or media – use old images in current news? Perhaps for “illustrative purposes”. But it may also have a negative impact: if you can’t trust the picture, can you trust the text?