Quote: "They must have some past troubles with sites and 'id' paramaters... Or maybe they've just got a vendeta against it"
With dynamic sites it's difficult for a bot to work out if a link is to a different content.
To run with adr's example say you had a product page of male shirts you where selling.
http://example.com/products.php?dept=1&pr
[/b]od=1
Where dept 1 is male and prod 1 is shirts.
You could also be selling trowsers
http://example.com/products.php?dept=1&pr[b]od=2
Where prod 2 is trowsers.
You could decide to order the items by popularity by default and optionally by price.
So to list male shirts by price
http://example.com/products.php?dept=1&pr[b][/b]od=1&order=price
This is a problem because they don't want to index the content more than once. It's very difficult for a bot to work out which paramaters result in different content and which produce duplicate content in a different order.
By way of demonstration, he emitted a batlike squeak that was indeed bothersome.