How accurate is the Google AdWords Keyword Tool?

[D4vid]

[adwords.google.com...]

It looks extremely useful on the service, but I'm currently ranking 3rd for a keyword with 22,500 local monthly searches & accordingly to Google Analytics only 148 visits last month originated from this particular search.

A CTR of 0.65% can't be right for the 3rd result, can it?

[BeeDeeDubbleU]

This comes up regularly and opinion seems to be divided. Try the search...
[google.co.uk...]

[NYCJester21]

Ultimately there's no way of knowing just how much of an impact you're having with AdWords. I've heard rumors of click manufacturing by Google that would muddy the waters of your total clicks or traffic.