As someone who spends a lot of time out in the forest of Colorado for camping, hiking, dirt bike riding, and hunting, let me remind all of you guerilla growing outdoors that TRAILS ARE EVERYTHING. The average person couldn't follow a trail of bread crumbs but the impact of almost everything is visible to the trained eye.
You can follow the foot steps of a mouse if you get on your hands and knees...so don't doubt that someone could follow your trail NO MATTER WHAT YOU DO if they are skilled enough and the terrain gives them enough to work with. Hiding your trail is art in itself but it's not that hard to figure out just make it look like it was disturbed (since you generally can't make terrain look completely untouched once it's been stepped on) but not disturbed
by people. Never entering from the same route is a start, trying to walk like you're hunting (read: step lightly and walk rather slowly) will go far because your impact will be less and you can note what impact you're having and correct it on the go (preferred) or on your way out (but then you're exiting how you entered, doubling your impact on the same general trail, therefore harder to cover).
Probably even more important is SMELL! I don't smoke cigarettes so it's easy to get a whiff of tobacco smoke, campfire, weed (including the smoke), exhaust fumes even from considerable distances. And smells come to you, you don't have to be looking for them whereas at least most tracks on dry terrain aren't immediately obvious to most people. Your average idiot could find a grow by following his nose if he was given the opportunity. And directed winds can easily carry what you'd think would be "little" smells a mile or more.
Sorry if I'm making any one paranoid but believe me it's warranted. I've never personally grow at all, period, much less outdoors (starting first outdoor grow soon)...but I have spent a lot of time finding myself curious enough to follow human activity in the middle of nowhere when I was originally there for something else.
I never go looking for oddities like plane crashes, abandoned moonshine operations, abandoned marijuana grows, abandoned hobo (bigfoot?) bunkers, abandoned rock mines, frontier (abandoned) cabins, abandoned hunting blinds, etc...
but it all starts with a trail. Except that one time I smelled something good then found like 3 pounds of ripe raspberries growing in a gully. That was great