It should be obvious from these letters that drive-by "lift it from the web, slap on own product" infringement is unpleasantly common. A person I knew in university has had book reviews lifted word-for-word from her site and used elsewhere for endorsement/advertising purposes. At least with text it's relatively easy to find identical snippets.

Without any attribution, I can only imagine how difficult it would be to track down an original photo once it has passed through a dozen different image sites.