Bing ignores robots.txt anyway: http://blogs.perl.org/users/cpan_testers/2010/01/msnbot-must...

It's a cut and paste from some sample file, so this doesn't indicate anything much.

google search for the text in the comments ( http://tinyurl.com/ygtuanh ) has 49 hits, there would be more if I had not joined the lines together, I'm sure.

Why is it useless (I've never worked with robots.txt)? Are the /css and /js files not large enough to bother skipping?

Look at the comments...

# robots.txt # # This file is to prevent the crawling and indexing of certain parts # of your site by web crawlers and spiders run by sites like Yahoo! # and Google. By telling these "robots" where not to go on your site, # you save bandwidth and server resources.

Useless in the sense it doesn't really need to mention Bing.

Blocking /css and /js makes sense because they don't add value in being crawled. Not necessary, but doesn't hurt.

Best practice: Always have a robots.txt file, even if it's empty.

What is the reason for your Best Practice advice?