Maybe I'm just the master of internal case airflow, but personally with the stock cooler my processor not overclocked yielded a load temperature of 45C. I picked up this cooler just for the heck of it(my processor can't overclock) http://www.tigerdirect.com/applications/searchtools/item-details.asp?EdpNo=5543190&SRCCODE=GOOGLEBASE&cm_mmc_o=VRqCjC7BBTkwCjCECjCE
It was $12 when I ordered it, and the fan stopped working within a month. I have been running it passively
ever since, and my current peak load for both cores is 39C. That's with 25C ambient so with a (currently 15$) cooler im seeing 13C over ambient with no fans on the cooler.
Granted my processor is only half of what an i5 is quite literally, but even then with a much larger heatsink with more heat dissipation capacity(heat pipes) and active cooling (fans) pretty good temperatures are very achievable with air cooling.(close to any modest water cooling setup) Check out the best temperatures some people have gotten with good air coolers before saying "there's no way close to ambient temperatures are possible with them"
Did you know there are plenty of threads I have posted in where people have a brand new water cooler(H50/H80/Antec 620) and they are getting high temperatures.(and want to know why) It's not because of poor general performance...... if all coolers performed poorly no one would upgrade from the stock unit!
The cooler can only be as effective as your own internal case setup. If it is not properly oriented to complement case airflow this is going to work against it. If case airflow is not even(intake:exhaust ratio) there will be either be hot air building up in the case(not enough exhaust/too much intake) or there will not be enough fresh intake air to keep the cooler as near ambient as possible(too little intake/too much exhaust creates a lack of fresh air available to the coolers own fans) This will effect a case like the cm storm scout to a much lesser degree than more common case designs, because of the abundance of mesh allowing free air exchange.
So on top of getting the heat sink mounted just right, you also have to make sure your airflow patterns make sense and effectively bring in fresh ambient temperature air to where it's needed most while minimizing turbulence. Getting the best temperature out of a given setup is not something you always get right the first time, sometimes changing around the fans and experimenting will make you realize a different more effective way to organize your internal case airflow, and you will be rewarded with better temperatures and potentially even a quieter case.