[QuantumIguana]

Malicious edits are unlikely. Someone would notice, especially if the book is from a legitimate source. It's just not worth worrying about. If the sample doesn't have DRM, you could use an online tool to convert it to TXT format, Google mobi to txt. But what would that tell you? If you already trust the files you have, then read those. If you don't trust the files you have, but DO trust Amazon, then get your books from Amazon. In order to test your files, you must have some known good source against which to test, and if you have a known good source, then use that. When is the last time you heard of malicious edits to books?