How an SEO Expert Knows they are over working the engines?

How an SEO Expert Marketing Specialist - Knows Googlebot is Tired of Scanning the Cache?

I figure that the obvious sign would be the "bot" warning. But then Googlebot seems to have a nice trick, unless I am missing something. You can see from the added screen shot I entered the "bot / harvester" code. Google over looked the need for a submit button here. I try to hit enter on the keyboard to no avail. Now that I think about it - I get this warning more during the day most times; maybe a power outage at google (here in CALIFORNIA - brownouts are when they shut the power grids down to a trickle... I wonder if they are marketing specialists doing steady one off SEO research search queries. Once you use up your 25-50 KW searches, cache review and other "hacks" it appears to shut you out until refresh... drop me a line if you are seeing this too.