I used to work in a small agency that did websites and Phonegap apps, and the senior developer was awful.

He had over a decade of experience, but it was the same year of experience over and over again. His PHP was full of bad practices:

- He'd never used an MVC framework at all, and was resistant to the idea, claiming he was too busy. Instead he did everything as PHP pages
- He didn't know how to use includes, and would instead duplicate the database connection settings. In EVERY SINGLE FILE.
- He routinely stored passwords in plain text until I pretty much forced him to use the new PHP password hashing API
- He sent login details as query strings in a GET request
- He couldn't use version control, and he couldn't deploy applications using anything other than FTP