I tend to favor earth tones and greens when in the woods, but I'm also not stealth camping. Here in the west, much of the land is "owned" by government entities. I view this as entirely illegitimate, and often direct evidence of land theft from indigenous peoples. As for individuals, if someone has not homesteaded the land, whether through agriculture or some other visible form of transformative action, I see little need to respect their claims, but one does need to still watch out, especially during deer season. Around here, there are some rules regarding properly posting property lines to signify trespass, too, but I don't know how that works in the desert.
Ya, if the land's clearly not in use and you're not damaging anything then there's no right to keep you off it, but if it is being used then be as respectful as you'd want someone to be to you.
The trespassing notice laws are the same out here as well. In New Mexico you need a sign every very short distance (can't remember the number), or it doesn't count. A fence by itself is meaningless.