I was a previous resident of Abu Dhabi for almost 2 years and I had a valid work permit. I resigned from my job voluntarily and returned to my home country without any problem. Two years after, I applied for a tourist visa to go to Dubai and boom, rejected! I applied again for three more times with some timeframe in between, and all were rejected.
During my stay, I've never broken any law or done anything illegal. It is worth mentioning that some people told me that you're blacklisted because you canceled your own work permit. It is really frustrating to be blacklisted for no apparent or legit reason.