I've hooked a few fish on the dangle.....here is my trick for ALL hook ups.
When you get the tug tug, or the neutral stop in the swing.....I pull straight back (rather sharply) rod stays PARALLEL to the water. If its a fish....you poke him and he'll shake his head (Which I counter with a solid strike (or 2) when I feel a headshake). If its not a fish, pulling straight back will usually set the fly free, rather than setting the hook into a rock, log, whatever. Before I learned this little trick.....I was loosing fish. Since then, I have only had one steelhead spit the hook. I'm at 75% landed of hookups. That little method has improved my success rate....so I stick by it.
If you want to experiment with it......throw on your heaviest sink tip, and tie on a fly that you dont mind if you drag it in the rocks. When you start ticking/dragging bottom.....rather than lifting your rod tip to free it.....pull straight back about 10 inches, and then release. I guarantee you will loose less flies and find an occasional hook up that you thought was a peice of bottom. I do this ANYTIME I get a noticeable strike, or my swing hesitates for any reason. Hope this helps.