Just a word of caution here -- you should view Bobby as if it were a spellcheck or grammar checker. It highlights possible issues, but cannot give definistive answers.
Compliance with web standards is 80% of the task of accessibility. Ensuring that content is available, usable, and understandable in multiple modalities (images, text, sound) is the other 20% and no tool can verify that.
The concept of "Bobby Approved" was one of the things I would have done differently if we* did it over.
*I was on the oriiginal design/dev team for Bobby