I agree that many advertisers seem to take SE rep suggestions at face value, and I think it is extremely naive. Just look at the default options for PPC accounts/campaigns in Google, Yahoo and Microsoft, and it is quite obvious they want to maximize clicks and price without much concern for your traffic quality. I used to think Google was the least sneaky, but their new move to hide the columns for conversions, cost per conversion, conversion rate, etc. is really underhanded, IMHO. They would rather get you to focus on traffic volume, hah!