Top ranking with 8 month old cache

What are they doing with bots

[extra]

I'm not sure where to put this question, but this is probably as bad as any other places.

A competitor has a cache (at g...le) that is nearly 8 month old. But still they are ranking on top in our local country search, and top half page 1 in .com search.
But when I'm doing this www.example.com/robots.txt search for their webiste to see what they are doing with the robots I'm forwarded directly to their homepage.
Doing same with my own site I get User-agent: *
Disallow:

Is there anything I can do to find out what they have done and why they have such old cache with TOP ranking.

[tedster]

Your browser identifies you as "not googlebot". If the site is redirecting everyone else but googlebot, then they may be using user agent (UA) detection -- a simple kind of cloaking. You can try switching your browser's UA to a googlebot string -- there is Firefox extension that makes this easy -- and see if you still get redirected away from robots.txt. However, if they are checking IP addresses for the redirect, then your browser alone will not help you do the detective work.

The old cache date question really belongs in the Google Forum. If you read around over there, you'll see that Google has been shuffling data sets around for months now between old and more recent. So from time to time old cache dates are pretty common, much to the chagrin and complaint of many. So what you see in the SERPs may be completely unrelated to the redirect.

[encyclo]

It could well be that any 404 not found errors are redirected to the home page, and they don't have a robots.txt file at all. Try typing in a random page name to see if you get an error page or if you get redirected also. You can also use the Live HTTP headers extension in Firefox to check what error code (if any) is served.