My helmets are old enough there's no problem telling which is mine except the forty year old half helmet has one Harley-Davidson tank decal on the back because it's pretty generic looking.
No stickers here. Give them some time and they just look ratty. Stickers on hardhats is a big thing in the workplace. Osha says no stickers, i personally dont give a crap either way as far as that goes, i just think a hardhat full of ratty nasty stickers looks unprofessional on a supervisor and that lends itself to the riding gear too.