handle of vacuum wand fell over and made small ding in drywall, right
below a light switch - so very obvious.

Reapired by filling with joint compound, sanding flat, and painting
with Dunn-Edwards high quality paint from the original 5 gal paint
container - to garrantee color match. Historically there did not
appear to be any 'primer' used over the drywall and taping, the paint
is the sealer and color, just sprayed on.

Yet, my repair doesn't look good. The finished repair has a 'ring
around it' looks like a water spot on my wife's silk blouse!

Ok, maybe this is a coating problem, so applied a second coat over the
1 1/2 inch diameter repair, and STILL it looks like a water mark. Ok,
third coat, still there!

Close examination, the joint compound in center matches wall, the wall
matches wall but the junction between the two makes for a ring.

Ok, maybe this was caused by sanding too smoothly on the junction. So,
very lightly sanded to rough up and make all the surface uniformly
textured using 120. Paint again, and there's still a ring!

Ok, I give up, exactly HOW am I supposed to patch drywall?