On my blogs I used to use a script that banned bad bots by adding their IP to a list on my .htaccess file. Until it crashed the banning script by adding over 5,000 IPs of bad bots in just 1 month. If my google analytics numbers were correct I'd say between 50% and 70% of my traffic were bots. So 61.5% sounds about right.

I've pretty much stopped looking at "number of impressions" when purchasing advertising too. It's always untrue. A recent blog I was going to advertise on said it had 35,000 unique visitors a month. But yet just a few weeks ago they had a "free give away contest for a jewelry brand (no purchase necessary, international readers allowed, free to apply, no shipping costs)" and only 100 people applied. That pretty much said it right there.

One more example: A site I was on allowed unregistered visitors to give their entire collection of corporate logos a rating between 1 and 10 stars. And they used radio buttons to vote for the numbers 1-10. As soon as you select a radio button it auto-submits and gives the logo that rating. EVERY SINGLE LOGO had a massive number of "1 star" ratings because all the bots would see a radio button, check it, and trigger the vote. All the logos on their site had a rating of 1.