Hi! I want to build a website on a niche so I followed the advice of some guys on a website that said Google AdWords: Traffic Estimator can be used to find the right keywords for getting the most earnings and visitor from Adsense. All I understand from this site is that some topics are more avoided by webmasters, maybe due te their level of complexity and so there are few sites in that domain. Also the CPC is huge, some have even 50$ per click… Is this tool to be trusted? If I make a website in that domain do I really get an average of 12-15 dollars/click?? I had Adsense on a site and I usually had 0.10.or 0.30 dollars/click so is hard for me to believe… 
Also if I there are so much earnings is that truly a niche and visitors will surely come without too much problems??
So if I find for a keyword like 10$ should I trust this estimation? Or it will be surely more less? Maybe like 5-6 $? And for some keywords like “cars” there is a monthly search amount like 600 million searches!! So if someone will get its site on the first 3 links on google when typing “cars” then he will have millions of visitors??!?
The AdWords traffic estimator is not related to the AdSense system in terms of pricing nor traffic estimates. Keep in mind that Google is going to take their cut of the price between the two services. If someone is going to pay $2.00 on AdWords you may only get $1.00 for hosting that banner ad.
Also, the traffic estimates given with the AdWords estimator are traffic for the Google search engine, not your website.
When I first started paying for ads i was kinda shocked that for web design ads people pay in excess of 5 dollars per click…because I too like you have sites with adsense and i usually get like 40 cents a click…But like jeff said before me the two tools (google adsense and the google keyword checker) are for different purposes. Their results should contradict each other but there may be some derivations due to their inherent different purposes…so in short. YES trust them. Use them both to the max