I have converted from lots of trail running to mountain biking. I've identified some of the problems with trail etiquette when it comes to MTBs.
1) Hikers and runners are too nice in CO. Although MTBs need to yield to all types of trail users, hikers will get of the trail 50ft before the biker comes to pass, and bikers will gratefully take the opportunity. Unfortunately, many have wrongly come to expect the courtesy from other trail users.
2) Strava. Some people are out from KOMs. It ruins trail etiquette and trails themselves (re: cheater lines)
My advice to runners based on my experience:
1) Don't yield to a bike unless you feel like you're in danger or they are overcoming you from behind and have made their intention to pass clear - exercise your trail rights.
2) Know where you are hiking at. If you are going to Apex, up the gut, on an even day, you can count on people blowing down the downhill direction. It may be a be a good day to do pick-and-sledge instead.
3) Thank them when they do the right thing; reinforce their good behavior.
4) Keep an ear open on the trails - you'll hear them before they'll hear you.