As newbee I don't understand Google SERP

[extra]

I'm a newbee regardig web design, and that could be part of the reasons why I don't understand Googles ranking (SERP). I'm probably not alone.
I'm among top 5 for most of important keywords (singel-dual-trippel) for my site thanks to WW. And I very happy with these positions and have no need for higher ranking as that will be wrong for some of mye keywords. But still I do look at those above me as I think other deserve those places.

One of those 5 using a lot of keyboard stuffing (hidden). But another company is using some strange technic that I can't understand (they are using some jave scripts).
All their cached pages was cached nearly 1 year ago. Doing a site search it says about 1500 pages. But only 50 shows up. Of these 50 pages there is only main + four second pages (probably their most important) that shows up. Rest of these 50 pages are pdf or pages with a singel picture only. Using www.example.com/robots.txt Their main page) shows nothing about their robots files. And they still among top 3 for all their important keywords.

Is there any way I can find out what they have done.

[tedster]

Javascript is not very likely to play into ranking. But there's one important factor you didn't mention -- inbound links from other domains. Not just how many there are (quantity is not what it takes) but how strong, how good, how old, how authoritative the linking sites are.

One warning - you cannot effectively study your competition's backlink profile using Google's link: operator, because Google only reports a sampling of all the links that they know about. But by using Yahoo and MSN you can start to fill in that part of the picture.

[extra]

Using Yahoo it seems like 99.9% out of 1500 links comes from their own company (pages with other languages). I don't know if this is sub URL domains, but I guess at least 2 of them are using same IP (maybe 1 with separate IP?).
There is about 10 links from other companies with TBPR of 3-5 coming from companies within same category.

Our company has only 600 inbound links, and the most important is probably Dmoz, but also 8-10 other serious 4-5 TBPR links from companies within same category. We also have some (50?) other inbound links from sites with less TBPR (0-3).

I don't think links from other parts of same company counts that much, but sure I don't know.
Earlier they had one more domain pointing to their main site, but now I can't find this site anymore.