I recently tried a Trijicon RMR 06 adjustable red dot. The dot appears fairly sharp in daylight at the range but starts to look a little more "star" or "paint splatter" shaped in low light even if I dim it to get rid of the "flare". Has anyone else seen this? It is most noticeable in very low light.

I have the dual illuminated RMR and I have a small star burst look in total darkness. It's the tritium that it has. It's never bothered me.

The issue may not necessarily be the RMR so much as it is your eyes.

When you are in dim light your iris opens up, allowing more light in, but in doing this, just like a camera lens, you loose depth of field focus and allow any inconsistencies in the lens of your eye to cause the smearing or star burst of the dot. In bright light, your iris is much smaller therefore you are looking through a much smaller part of the lens, right in the center.

Red is particularly bad about this because it is at the end of the color spectrum and has more diffraction than any of the other colors.

If you have had Lasik, like me, you are specifically susceptible to this issue. In low light I have some serious issues with my red dot looking like a red smear rather than a dot.

That explanation makes sense. Now that you mention it, my green fiber optic bow sight pin looks smaller and sharper than my red one but they are the same size. The good news is that the dot changes I'm seeing should be irrelevant for deer hunting.