Search Results Filtering?

I recently read that P2P networks were forced to remove results for common
queries such as "Madonna". I am beginning to suspect that search engines do
similar things in order to suppress piracy, but they cripple genuine sites
in the process. I am merely trying to find sites where legitimate songs are
offered for download.

I have come to realise that various sites, which I re-discover time after
time, slowly die. They sometimes disappear or get emptied (many of them are
Wikis/feeds). Also, it seems like search engines /might/, just might, filter
search results which should correspond to such sites.

Is that nothing new? I thought that results of ranking algorithms were only
'massaged' in China...

Roy