This is a good question. I am of mixed mind. Based on personal observation, there is something "funny" about bigfoot vision. Seeing into infared would account for those observations. The problem, though, is that trail camera triggers do not use projected infared. The only time a camera produces anything infared that could be seen is when the IR flash goes off and the picture is being taken. The only way that could alert a bigfoot to the presence of the camera is if bigfoot happened to see the camera flash when it takes a picture of something else. I do not think seeing infared accounts for them avoiding trail cameras, not by seeing anything the trail camera is producing anyway.
I have another notion. In the way of an experiment, I set up two trail cameras facing each other, one inert, the other active, then triggered the active camera to take a picture which I observed. The inert trail camera was not camouflaged under the IR flash, it was a solid color rectangular box. If bigfoot is truly seeing cameras and avoiding them, then it might be because though the cameras are camouflaged to us humans, they are out of place solid color boxes to bigfoot eyes. If that is the case, then we need to completely hide the camera within some natural material so that the plastic is not visible. I don't have any cameras out right now, but when I do, I cover them with tree bark, burlap, leaves, or the like, and I attach them to trees with black wood screws and thin black wire rather than wide straight straps which are eyecatching.
Hmmm .. one of my friends has one of those rock cams .. a trail camera built into an artificial rock. I'll ask him if he has a regular IR trail camera and if so if he could take a picture of his rock under IR with that camera to see if it is hidden or stands out in some way.
MIB