Yes, it is possible to spray paint faux flowers. But there is a catch. The challenge is not ruining the realistic look of the flowers when you are painting them. In the real world, flower petals do not have uniform shade everywhere. Most flowers have a lighter shade towards the inside and a darker shade towards the outside. You will have to use the paint carefully to replicate this effect when you are painting. Also, use floral spray paint instead of regular ones. They dry faster and do not form a thick layer on top of the flowers.