matrix_jan - 1:05 am on Feb 7, 2013 (gmt 0)

A visitor uses their browser's bookmark/favorite to access your site, thus sending no referrer.

Again, the page has no referrer but images do have and it's their parent page.

Well, the thing is that those who see my website with no images most likely might have not even visited the page if I had allowed hotlinking, because I get a lot of traffic when I block blank referrers(except from some bots). And from that point on it's their problem...

My guess is that 99% of internet users don't know how (and why) to block referral data. And the rest, 1%, are not "valuable" visitors because they're good in tech and rarely click on ads.