I found Cliff Racers to be a very minor annoyance, but i found Dragons to be a huge one.
Cliff Racers:
Initiate combat while staying up high where you can't reach them.
Dragons:
As tough as any other creature.
Flies around looking cool for a very long time, while initiating combat. (you think dragons would be a bit more aggressive, but NOOOOO!)
Leaves Glitchy huge bodies.
Comes to frequently.
Dragons are not really deadly creatures, they just look cool.