I don't know how practical the advice still is today, but traditionally those doing candid photography preferred equipments that are as less conspicuous as poss

I don't know how practical the advice still is today, but traditionally those doing candid photography preferred equipments that are as less conspicuous as possible, that's why Leica has been so popular among photojournalists. Henry Cartier Bresson, they guy who pioneered photojournalism, used to wrap black tape around his Leica to make it less distracting to his subjects.