I couldn't car less.
Join Date: Nov 2003
Bikes: Ritchey P-series prototype, Diamondback, Nishiki Triathelon Pro.
Scar tissue does not hold ink well, but a good artist can work the scar into the design and not ink the scar, i've seen this done for women with masectomies, and fellows with bad scarring.
Avoid areas that have a large amount of sweat glands, the ink washes.
On the back or inside arm upper can be quite painful.
My spine was no problem, 4 inches over to the underside of my shoulder blade was hell.
Lower back was painfull too.
I think the calf is a good spot, depending what work you do, and if you care what others think, a decision to do the upper arms only above the sleeve of a short sleeve shirt.
An idea also is not to get really tight detail lines as over time the ink spreads under the skin.
Celtic knotwork used to be really popular, but if the detail is too small and tight, in a few years it looks a messy block.
Leave some space -in a few years the lines can be re-inked and it will still look good.