Lyric discussion by saves_matts_day 

Cover art for Placebo Effect lyrics by Siouxsie and the Banshees

I think it is about "alernative medicine" in particular. The first verse is about "psychic surgery" where phsycics claim to have fixed internal problems without even touching the patient. The second verse seems to be about acupuncture. The verse about colour is about new-age medicine - using colour to change mood, calm hysteria or anger etc. That's my take on it.