There are dumblaws in alot of states though they aren't enforced.When a cop does enforce them.They are usually the over-sealious bastard or they are lazy and want to get there quota up.
Often enough, if they know you're doing something they can't gather enough evidence to bust you for, or if you'd just up and pissed them off, they can dig up something to bust you with.

But most of the dumbest ones just go unenforced--can you imagine the laughingstock a town would be if it busted someone for walking across the street with an ice-cream cone in their pocket, or for taking a bath in November?