Sorry bekyed, I'm afraid I'll have to respectfully disagree with that as a blanket statement. First off, not everyone around is a professional SEO, and given enough time there are certain things that when done can and do reliably contribute to high rankings. While it's true that a certain amount is trial and error, after some individuals have done a certain amount of trial and error testing over time their mileage and perceptions are not necessarily at the same level as others.
Point being is that it is not ALL trial and error, though for some individuals it's more so than for others. Also, there are certain things that aren't even subject to trial and error, which in some cases can be a perilous route to take, the safer way being taking calculated risks based on known probabilities.
Getting back to the specific issue, there might just be something else involved.
viggen, there's another domain with the exact same URL, even with the .com - with the exception that a two letter country code follows it. No connection, no funny stuff, and it's in another language. But the presence of the .com in the url (as opposed to being like co.uk) may possibly be causing Google some type of error or confusion in including your site.
This is why those papers out there are so fun and exciting to read. Check this out in Hilltop: A Search Engine based on Expert Documents [cs.toronto.edu]:
Not saying this is being used for certain, but there has to be some means to identify affiliation. Which would be the unique rightmost token in the domains concerned. Could they possibly be considered to be affiliated in this particular case, even though there isn't the remotest connection between the two?
Let's look at these:
And then at this
If you look at the backlinks for that last one - for which the PR is 9 not 10, incidentally, it is showing the backlinks for www.google.com - obviously in their case they're aware of the affiliation. But no way are those sites pointing to Google's .com.tw domain.
Again, not saying that Google is using this in the particular instance we're now discussing, but given the possibility, even if it's vague, I think I'd be inclined to write to Google again and ask them to take a look specifically at this particular issue. It certainly can't hurt.
I'm inclined to suspect that this may be a possibility in this case, well worth looking into.