My search results are including many duplicates and are linking to pages that are not there, I think probably these are revisions as they have URL like '2011/10/6025-revision-2/'.
My first thought was to rebuild the index, which had no effect. I then made sure that the index was being rebuilt by adding log statements to relevanssi.php; it appears to be reaching relevant parts of the code.
I then wondered if relevanssi was indeed being used. I disabled the plugin, searched again (this time no duplicates or 404), then re-enabled, and got bad results again.
I've searched extensively for anyone with the same problem and found none, so either I'm doing something fairly stupid or very obscure. Any help would be much appreciated.