I often see a visit to a home page followed in the next few seconds by a spider all over my site. I used to think one person viewed the home page and left, but some one told me they visited my site the other day and looked at all my pages, but it only shows in the logs as a visit to the home page, then the spider. I am not sure whether I believe them or not.
Is the spider retrieving the pages for them to view offline or something? BTW, the ip addresses don't seem to fit for that.