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Exactly what the subject is - what is the cause of this and how do I fix it?

At first I thought it was over-extrusion, but I calibrated my extrusion and nothing has changed...

Ideas?

Printing ABS at 228 extr and 80 bed, .1 layer height, ambient temp ~19.

http://imgur.com/a/ErdLU

Thanks!

It's too hot. The plastic in the overhangs is drooping before it solidifies.

Lower the temp, or add cooling fans. You can also print multiple marvins at the same time to spread out the heat and give each one a little longer to cool between layers.

Great I will lower the temp and see what I get - thanks!

That part won't print well in ABS with a lower temp. It's just too small.

Print 2 or 3 at a time and you'll get better results.

Cooling fans and ABS don't mix well, but since that part likely won't warp and you only need the fan for the key chain loop, you could turn a cooling fan on when it start printing that loop.

The thing is, this his happening with larger models as well (or at least the layers with fine details on larger models).

Not only that, but the quality on most of the part seems pretty damn good.

Is there a way to tell the program to take more time with layers that take less time to complete?

Yes there is. There is a minimum layer time setting in most slicers, an option to slow down printing when it comes in under time (Other wise it just lifts off the part), and a minimum print speed setting.

A cooling fan WILL help with this part.

Here's one printed in ABS at 0.1mm layer height, I think around 230-240 degrees, with a weak cooling fan aimed squarely at his face. Make sure it's weak, you don't want much. My fan was a good 50 cm from the edge of the build plate. Note that the keyring part on his head still needed more cooling, I should have moved the fan closer when printing this part.
Also using a flying extruder, and tweaking your bridging settings will help a lot.

Also I think the issues with your benchy model are to do with retraction length. Speed up your retraction, use less retraction, speed up non-print moves. You want that nozzle to zip across so fast that it doesn't have time to ooze.