Why would Google not re-index sites?

Any ideas?

[namniboose]

I have a question: does Google sometimes not re-index sites?

A couple of sites I am monitoring are still showing old titles and the cache hasn't changed (I made changes weeks ago). Both are well-linked and have the correct robots metatags.

Why would they not be re-indexed? I am getting nowhere with these 2 sites - it's very frustrating.

[lazerzubb]

They have limited amount of space, and limited amount of time to index and store data, Google has stated that they sometimes have to drop pages etc from the index. (i know your pages weren't dropped)

Can it be that the changes where made after the last crawl?

I've had pages which have different content on them, and still show up for the old keywords with the old titles, so they have sometimes duplicate copies of your page, try using Site:www.domain.com domain
and see if it still turn up with old titles etc.

[namniboose]

Hi Lazerrub,

As I said, the changes were made weeks ago and I have been searching under www.domain.com

Actually I thought I had made the changes in time for the December update but figured I must have missed it. Now I'm not so sure.

Any other ideas?