Maybe when they are feral!
Not normally
(if there eyes glow they do this)
i always dreamed of feral zombies being scary due to there agility and there persistence
(able to climb walls (poorly but still able to), leap farther, able to Block attacks for the cost of their arm , hop on cars, , Roaring to lure more zombies, When they turn into clawlers they Crawl themselves to you at a fast speed and Leaping! Able to infect you faste. Having blood Red eyes and veins....
That would make people S*^t their paints, that would madmole Hide, it would make me not want to go out at night, it would make roland want to knuckle rub himself to death!