Coyotes are strange critters. You can haul road killed deer out to where you want them and the coyotes are all over them In few days. And the next deer you haul out to a predetermined location and that deer won't get touched and just rots away.
I found a deer that had been pulled down by some coyotes. It was partially eaten . It was In bad place for setting traps so I moved It a few yards to a better location. That deer was never touched again It just rotted away.
I agree there is something we don't understand about that behavior. I've seen the same thing -- some animals consumed in a couple days, others never get a sniff. One thing I have found is if you open the viscera of an animal and then drag it, your odds of coyotes eating it increase. Also, if you have cut up pieces -- the size that coyotes can carry off -- they are much more apt to do so than starting from scratch to eat the whole thing. I've also found that if I dragged an animal to a good spot (open clearing area where coyotes can see all around, away from highways and other road traffic) and then left it for the coyotes to start eating on it before I set any traps, not only were the coyotes more likely to eat on it, I caught more coyotes there because of all the advertising done by other coyotes. Like I said, there are some other things at play that we don't understand but if you get them hitting a bait, you're in the clover.