The lowest adword bid is 5 cents. If your per visitor earning from adsense is more than that (lets 10 cents per visitor), it's possible to pump up adsense earning by running adwords. My question is how much traffic you have increased by running adwords?
i couldn't see it being much traffic if you are spending 5 cents and averaging 10 cents per visitor. I'm assuming that 50% of your visitors do not click on your ads, there for most likely what keywords that pertain to your website are expensive... and to drive decent traffic you would have to be on the first page really.
you'd probably be better off buying words on one of the low cost PPC engines out there that let you do 1 cent/click and trying to convert that way. That way, you need a lower % of people to perform the action (ie clicking on adsense) to pull a profit.
I did a lot of trial and error. If you’re not able to pay for top position, at least in my case it was a waste of time. For the primary keyword I was bidding on it was over $5.00 for a good position.