The spots above don't seem consistent with the AO ray bias being too small (although it's a little hard to tell from the above image). If you are using the AO node on a material that doesn't have displacement mapping, a ray bias of 0.4 inches should be fine, but in doubt - increasing to 0.7 should remove any blemishes. If you've got a rough displacement map, then a larger bias might be required. Try rendering the above with displacement mapping OFF in your render settings. Artifacts can also be caused by ray-traced shadows (and a very light ray bias on the light). If you turn OFF ray tracing in the render settings (which will turn off AO and Ray traced shadows), do you still get the artifacts?

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Creator of OctaneRender for Poser
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