Ah, nice strawman from hyperbole. Well done.
Sounds like you don't have much outdoor experience. Some of the answers are obvious to me but I'll point them out for your benefit. 1) Running water generates a lot of white noise which masks the sounds made around it. FWIW, that's why I don't camp creek-side, I back away a few hundred yards. I like to be able to hear. Still, I have to go to the creek for water so there is a period of vulnerability. 2) There is generally a breeze up or down canyons. Depending on which way the wind was blowing, all scent from the guys, horses, and gear may have been moving away from Patty. It is hard to smell that which is downwind of you. This factors into a debate I had with Henner Fahrenbach. It also factors into a puzzle in my own research area where 'whatever it is' remains upwind even when the wind changes. 3) Horses have a quadrupedal gait, they don't sound like humans moving, so it is very possible Patty knew they were there but mistook them for deer or elk until they rode out of the brush.
There are probably more but that gives you a general idea how naive your assumptions are.
Y' know, I've seen two at different times and probably a third. Whether they exist or not is a moot question for me .. duh, of course they exist. Discussion of whether they exist is like sitting around Monday morning rehashing how the football games should have gone. Should, shouldn't ... absolutely irrelevant. Even if I agreed, the score from Sunday stands.
What matters to me is HOW. I'm not entirely convinced they have any special abilities. It is at least equally possible we vastly overestimate our own abilities. If you insist on underestimating your ... foe, enemy, competition, or whatever you choose to call them ... the chances of us achieving our goals (official discovery) rather than them achieving theirs (non-discovery) drops to nil. We are doing that by insisting we can only be chasing a dumb ape.
MIB