Why do they cotton swab the guy's arm with rubbing alcohol before a lethal injection?

To make sure its clean so when they reuse the needle it doesn't give the next guy aids before killing him.

Per wikepedia: the arm of the condemned is swabbed with alcohol before the needle is inserted. along with its antiseptic use, the alcohol also causes the blood vessels to rise to the skin's surface, making it easier to insert the needle. the needles and equipment used are also sterilized. one reason for this is because the needles are standard medical products that are sterilized during manufacturing. also, there is a chance that the prisoner could receive a stay of execution after the needles have been inserted as happened in the case of james autry in october 1983 (he was executed eventually on 14 march 1984). finally, it would also be a hazard for those handling unsterile equipment.