Companies look at things very differently than one person does. They don't want to waste their resources on someone who will leave for a better opportunity. Why put you through all that training, and getting you up to speed on their systems, just to have you leave? It doesn't make sense. If you have a long history of quitting, you will have an even harder time, even if your resignation was in a respectful manner.
So what do you think? Do you have a lot of jobs listed on your resume? Are you a short-timer? Or have you been laid off and are having trouble finding work due to this unfortunate blackballing practice?