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make sure you circle your chosen spot a bit to make sure you aren't right next a trail, path, gametrail, skunk den, etc.
one time when i was teen-aged we camped in a local state park, thinking we were well and truly inna middle of nowhere after wandering off trail a good 20mins. then at like 11pm a bright flashlight passed our camp about 40ft away. turns-out there was actually an unmarked trail going past that we hadn't noticed because we didn't investigate around enough. through the thick woods they didn't see us.
we think it was the ranger (apparently they do sweeps when they hear people after dark or smell a campfire) as rogue camping is restricted in that particular park.
but yeah, just check around a bit to make sure thing weird is nearby in general.