I've caught a few episodes and the folks on foot don't seem to be doing all they could do to be as invisible as they can. I'm sure that they are given suggestions to make the show interesting, but if it was a real life/death or freedom/incarceration thing you can bet that I'd be much more careful than the contestants.
As for throwing the tracker off their trail, I have no experience doing that. It would be fun to try out some stuff though.
I suspect that the terrain they choose makes it somewhat easy for the tracker to predict the path the people on foot will take. It seems that the waterways, mountains and trails all lead in one particular direction and if the tracker misses them in one spot, he can most likely head up the trail and pick up the scent. I could be wrong, but tv isn't always truthful or fair to the viewer. Fun show anyway from what I've seen so far.