Note the opening sentence of the 12 page pdf document:
"Web spam pages use various techniques to achieve higher-than-deserved rankings in a search enigine's results."
Source:
http://www.vldb.org/conf/2004/RS15P3.PDF
Then, note the last post in the thread,
what is spam:
kgun wrote:
SERP Spam:
By SERP spam we mean any thechnique, not related to content, that results in a manipulated position on the SERP's of one or more SE.
pemburung wrote:
SERP Spam:
pages on a SERP that are not relevant to the search term, have been manipulated to artificially raise their SERP rank over that which would be achieved normally through content, relevancy, and good design, or serve no useful purpose for a searcher. Also, the use of techniques, legitimate or otherwise, to achieve this.
DrTandem1 wrote:
Spam
is any repetitive use of a term for the sole purpose of artificially increasing SERP ranking.
This may end as a very informative thread if we could get some more constructive proposals. Then we may agree on a synthesis.
Do you see the relation?
And from the same abstract:
"We first select a small set of seed pages to be evaluated by an expert.
....
Our results show that we can effectively filter out spam from a significant fraction of the web, based on a good seed of less than 200 sites."
And note the last sentence in the conclusion:
"In a search engine, TrustRank can be used either separately to filter the index, or in combination with PageRank and other metrics to rank search results."
Important, interesting.