There's a disgusting reason public bus seats have that ugly pattern. Apparently, those seats are designed in a way that will trick our eyes and distract them from seeing all the dirt and grime they're hiding.
It's not something you want to think about it ever, but you might want to bring a towel next time you ride a bus.
Oh and if you really want to see just how much gunk those seats can hide, watch this cleaning of a bus seat.