There has been a lot of discussion regarding UAE have a 'dress code'. Recently Emirati's have commented on the way people should dress modestly in the UAE and respect the culture and religion of the host country.
A campaign was launched by two Emirati ladies on twitter : UAEDressCode.
One of their comments was:
As a guest, you're welcomed to our country and everything you think of is provided to you. So be grateful & show some respect to the people.
I read an interesting article about the topic in the Khaleej Times which gives expat's views on the topic too.
The famous Expat women website also has a guide to the Dubai dress code.