the worst thing is when your system cant handle these "increased error rates" as your control plane cascades failure due to something like this....
The worst "increased error rate" problem I had was when the API was failing and my autoscale system couldnt deal and launched thousands of instances because it couldnt tell when instances were launched (lack of API access) and the instances pummelled the fuck out of all other parts of the system and we basically had to reboot the entire platform....
Luckily, amazon is REALLY forgiving with respect to costs in these (and actually most) circumstance....