I disagree with the title of this thread..
When doing arbitrage, you're mostly (or supposed to be) targeting niches with payouts per click on an avg of $1 or more. Hell, even $0.60 per click is good, just so long as it has the traffic volume. With that said, there are tens of thousands of advertisers who use adsense usually by default without even realizing it (thanks Google for auto-checking it!) and I'd say that MAYBE 1%-4% of advertisers (mostly small advertisers checking for max ROI) will notice this and MAY do something about it. The guys paying dollars per click see Adsense as a way to not have to pay as much as search, and with the tremendous amount of sites showing their ads, the chances of them killing it are seriously, slim to none.
But... if you want to jump the gun and pretend like this will have an effect on your earnings, go for it. But you're just scaring yourself and that's all there is to it.
Remember.. you can make 10,000 sites for the same damn niche, with the same damn content if you really wanted, and arbitrage the shit out of all of them the same damn way, and do you really think advertisers are going to mull through each one and see who is converting and who isn't? Fuck no! And for the few that do? Well, there will most likely be 5-10 more advertisers who could care less that will replace them.
So arbitrage on my friends.