For you Western riders - What exactly is "spur training?"?

Being an English rider, occasionally I hear references to Western horses being "spur trained." Now I frequently wear spurs when I ride English, particularly to enhance my aids for lateral work in dressage. The rider needs to have control over their legs so they are not pricking the horse with the spur needlessly, but you don't have to train a horse to accept spurs. I have a feeling you Western riders mean something very different by "spur trained" and I'm curious!