For me, scary isn't about big rocks or technical stuff. For me, what makes a trail scary (that is the thread title) is the CONSEQUENCE of a mistake. On something like black bear, the consequence of a mistake might be certain death. On others (like going unprepared into the maze district) it is about being stranded. I had a very seriously scary encounter where I almost buried my jeep 9000 feet in the air at La Sal Pass in Moab, before all the snow melted. There was zero trail traffic so getting stuck there would have been a really bad day. The key is to not panic and keep control, or else the situation will only get worse.