Great thread ... about taxes, but I cannot but notice nobody is actually replying to Scott's question.
Scott. I have not worked in the Middle East, but yes overseas. In the past I have got about 0% to 40% to 50% but it really depends on the market, place, length of assignment and conditions.
As you probably know, there are also other considerations, taxes (I ask for the company to pay local tax if any), living arrangements (decent & paid for), holidays, expenses, flights, working hours (if you have to work 10hX6d, suddenly the 40% premium results on a hourly rate cut!), health and life insurance, responsibilities... The usual.
I find that other conditions, rather than pay, will condition me saying yes or no to an assignment. I have run away from places that paid "tons" and worked happily for my normal rate in others.