Griff, I've snared thousands and I've witnessed it, so has pegandgun, so my minds made up.. maybe not all the time, but it does happen..
Head over to any American trapping site and you will find many animals over there that can become snare shy, from beaver, coyote, etc.. some do see snares... it's off topic, as were talking about rabbits, but animals have a sixth sense sometimes, and I'm 100% sure they do see snares, some do not see them as a threat, like a piece of foilage, grass or whatever, but some do shy from them.