Can the source of your traffic affect AdSense revenues? Jeremy Zawodny thinks so in an interesting piece of subjective research he muses:

Digging a bit deeper, it's interesting to look at the click through rate (CTR) for various sources. Here's where the numbers get interesting. It seems that AOL and MSN users are more likely to click. Ask.com users aren't far behind. Yahoo is in third place with Google trailing by a fair amount.

It's always interesting to read personal analysis on this kind of topic, particularly from an esteemed blogger such as Jeremy. It all adds to the rich tapestry of research appearing on blogs all the time - some more relevant than others. But, "one swallow doesn't make a summer" and quite frankly from my own experiences and talking to other bloggers I have found little to corroborate Jeremy's conclusions. There are a large number of factors at work here, most of which we will not understand (unless of course you have access to search engine user demographics and can point to some obscure correlation to CTR's and owning a car!)

The point I'm making here is that it's always important to take this kind of analysis with a pinch of salt and reading between the lines I think Jeremy intends it that way. What Jeremy's data does do fantastically well, is to point you in the direction of quite possibly the most important site research you'll find on the web - quite simply your own.