Missouri implemented purple paint years ago to signal No Trespass.
City slickers will paint every tree they have on their high dollar deer leases kinda funny.

Maine has what they refer to as "implied access". What it has meant traditionally is if your land isn't posted I can roam it without consequence. That has been the generally accepted tradition in Maine for about forever. But times are changing and while that thinking still applies to a degree, seeking permission is strongly advised by our F&G Dept..

Purple paint is one of the prescribed methods for legally posting your land here.

It's a lot easier for Johnny Sneakum to tear down a poster than to bring a can of paint and cover all the purple blazes.

Is it legal to just go on anyone's land if its not posted there? Do as you please, fish, hunt, trap???

Trespassing on elk hunting land in the mountain states is a huge nono.

ADC, No. If hunting or trapping it is up to you to know the boundaries of the land you have permission on.

My uncle had trouble with trespassers for awhile. He finally got sick of it. He was known up until his death as the guy who would lift your truck up with the forks on his tractor if you parked on his land. The funny part was, if you asked him he gave anyone written permission to hunt.