Failing to deliver promised research
There is a huge difference between saying that you will do a given research effort, and saying that you will obtain a particular result. If you have guaranteed the latter, you made a mistake, it's research, there is no guarantee on a result !

So, if you give a work planning to your adviser, you have to stick to it. Of course, you can have (once, not twice) a real problem that ruins your effort (house on fire, a relative at the hospital, etc.).

To summarize, you can promise that you will work, but not that it will work ;) If you always fail on your commitments, you will never be seen as reliable, and people won't work with you, it's that simple.