Reliable or Dependable?

Are you reliable? or dependable? I find that the fact that I am dependable usually over-powers any other inabilities I may have. I have also noticed recently how flaky some people are. 1 time of not following through on your word is an accident, 2 times not following through on your word is a flake, and 3 or more times of not following through on your word makes you a liar. I hope that doesn't sound harsh, I just have been trying to work with people a lot and I find that most of the time, like 90%, they do not follow through on what they say or promise. What is that about?