SEO - Deep linking

#! is an infrequently used token in existing hash fragments; however, it is not disallowed by the URL specification. What happens if your application uses #! but does not want to adopt the new AJAX crawling scheme? One approach you can take is to add a directive in your robots.txt to indicate this to the crawler.

Disallow: /*_escaped_fragment_
Please note that this means that if your application contains only this URL: www.example.com/index.html#!mystate, then this URL will not be crawled. If your application additionally contains the bare URL www.example.com/ajax.html, this URL will be crawled.