Scribd Search Engine Optimization Features for PDF

All recently noticed that PDF documents in Scribd are also SEO friendly for search engines. For example the link http://www.scribd.com/doc/17135767/FREE-by-Chris-Anderson

If you open the page and see the HTML source code, the plain text from the PDF is not presented. However if you open the cached version of the page from Google search it appears a tag html_wrapper which contains the text from the entire PDF document. Do they display different content depending of User-agent that make the request - ex. browser or bots? I've heard some SEO practices that don't recommend displaying different content for bots? How bad practice is this from SEO prospectiv开发者_开发技巧e?

this is what google sees

http://webcache.googleusercontent.com/search?q=cache:-LY7o-liYlsJ:www.scribd.com/doc/17135767/FREE-by-Chris-Anderson+site:www.scribd.com/doc/17135767/FREE-by-Chris-Anderson&hl=en&strip=1

yeah, you should not display googlebot different content then a human user, said that there are ways to do ok conditional rendering (i.e.: render for no cookie clients, render for no javascript clients, render for clients without a language header, ...) this kind of rendering can be missleading, but if is not missleading then it might be ok for google. if you do this kind of conditional rendering it's then always a question of intend.