incrediBILL - 4:05 pm on Jun 11, 2010 (gmt 0)
Depends, how big is your site?
I have 100K pages and a spider can spend hours poking around.
Some scapers/spiders only hit a page or two and run away, others try to take hundreds or thousands of pages at a time.
The only real conclusions you can draw that it's not human if it takes too many pages too quickly, downloads way more pages than a human can read, or stays on your site for a very long extended period of time.