What I check for when I do code review for AMO selenium tests

code review checklist

Filename matches first classname
    * filename is lowercase with underscores between words
    * class name is camelcase and THE SAME as file name

Files with tests do not contain "self.selenium"

Locators are in CSS -  (btw css can do children)  
      http://www.w3.org/TR/CSS2/selector.html

Check the locators with firefinder

Is it random enough? - tests should not rely on the presence of a particular addon unless it is a test specifically for that addon

Will this test/page object over-write other work being done - it's always worth having a glance through the current set of pull requests to make sure there won't be any duplicated code:  
https://github.com/mozilla/Addon-Tests/pulls