Traditionally I use FireBug to debug my AJAX requests. It lets you examine both the contents of your request as well as the response that was sent back from the server. (it
Turn on resource tracking, then check the resources tab. Resource tracking seems to work a lot better if you check "always use resource tracking."
I encountered the same problem: POST request from flash + JSON response + no response displayed in Chrome inspector. No problem with FF + FireBug though.
Adding charset=utf-8 to Content-Type in the response headers solved the problem for me:
Content-Type: application/json; charset=utf-8
I'm not sure if this is the proper solution for this issue, but at least I'm able to see now the JSON response in Chrome Inspector.
In the fail callback, the first parameter has a property called responseText.