Ralphie, to be a pedantic Chemist,Racemic is a a mixture of Left(L-) and Right(D+) rotatory molecules and therefore shows NO rotation but has the chemical props of the Tartaric acid, (You can seperate the crystals of D and L Tartaric with tweezers as the they are distinctly different)
The other part of the Dexter and sinister mystical argument is to do with the left being the mirror image of the right and brings in the atavistic and sinister "alter ego in the mirror" that looks the same but is left handed (in a predominantly right handed world)and may be the "darker" side of the person looking.
In some circles when receiving gifts, or magical objects that one is uncertain of the provenance of, the gift/object is recieved and taken in the left hand so as to limit the access of its energies to the recipient, as the left is regarded as the more controlled, less open and accessable area of the recipients body and energy (and of course V/V for left handers).