Hello,
I regularly receive offers to work as a real estate agent in Dubai (through Monster - I've worked in a real estate agency, negotiating sales, so that's probably why they keep 'harvesting' my CV). The last one I had, they were offering £20K pa + a commission on 20% on sales or 50% commission on sales.
Even if there is no income tax, £20K pa will not be enough for you to live correctly in Dubai. Rents in particular are very expensive. That's if you do get paid of course: a lot of expats (for example construction workers or hotel/restaurant staff, from India, Bangladesh, the Philippines) complain about their employers being several months' late to pay them... Some employers (expats in particular) also vanish without a trace.
Two of my neighbours (a French-American couple) worked for 1 year in Dubai, between 2008 and 2009. They were both in the financial industry. They were 'lucky': they had not got on the property ladder (no mortgage), so when they lost their jobs, they were able to headtail it back to France. They did not get any 'moving out' package and had to request a donation from the bank of Mummy and Daddy to pay for their return fare. If they had had a mortgage, and had defaulted on it, they could have ended up in jail.
Right now property does not sell well in Dubai, so you won't make a big living from real estate. As to the financial industry, I'm afraid the bubble has exploded as well. The only sector which might be doing well is tourism.