OK not sure if my experience was truly like yours but when I was in AD I didn't have a visa or work permit - nothing! We had to do visa runs every 8 weeks with an extension inbetween! This went on on for more than 2 terms. I didn't have any trouble coming into Dubai (my flight left/returned to there) but I did have all contact details for HR dept beforehand. I was questionned once by immigration on going out for a job interview in Germany - they were concerned with the amount of stamps in my passport. I was held for approx 1 hour but eventually allowed to continue following a telephone call and lots of questions!