We are not going now, due to a conflict. But we went on a 3 hour trail ride last weekend and didn't encounter a single 4 foot tall dog or mattress on the trail! We did have to go onto the road and cross a bridge, and cross white and yellow painted lines. And we went past some gravestones. I still want to get out on a judged pleasure ride one day.
They are fun to do but 'real' trail horses often take great exception to fake obstacles. My DH's first QH was an exceptional trail horse- and he was terrible at obstacle competitions, epic fail
My mare does decently on the pretend obstacles, but she is a star with the real stuff, so I am not complaining. We've done operating oil wells, a guy in a kayak within touching distance while swimming in the lake, a hot air balloon landing near us - really, who cares if she does the swim noodle carwash? I honestly think it is the easy and obviously safe way around that pretend obstacle that throws the real trail horses. They are smart, and have to use good judgment on the trail. Obviously, the normal arena footing is a better bet than the swinging bridge. (And sometimes the pretend obstacles aren't that well put together, and it turns out the horse that refused really IS the best horse!)
I have done several judged trail rides and none have been in the ring. they have all been done along a regular trail. Might ride 20 minutes before you come upon an obstacle. Most of the things in a judged trail ride I have seen oin just a regular trail ride.