An antiseptic was a substance that prevented bacterial infection; while something that was absent of bacterial infection was said to be aseptic.
In 2364, while monitoring Lore's activities on board the USS Enterprise-D, Data found his interest in fine grind quadratanium to be no more suspicious than a Human searching for an antiseptic or an ointment. Despite this fact, he still planned to investigate. (TNG: "Datalore")
The term could also be used to describe a method or version of something which lacked the appeal of the original. In 2268, Harry Mudd bemoaned the changes that Norman and his android compatriots wished to make to the galaxy as being "wholesome" and "antiseptic", adding that for someone like him, it would become a "purgatory". It was what ultimately convinced him to aid the crew of the USS Enterprise in thwarting the androids. (TOS: "I, Mudd")
In 2372, Quark found the Karemma's business ethics far too antiseptic for his liking, as they believed in setting a fair price for commodities rather than cheating their customers. (DS9: "Starship Down")