Hello, and yes I am also one of those who work at Dubai,
There are various factors at work here. Just to put things a little in perspective.
When an aircraft doing 320+ knots passing FL105 ask if there are any speed restrictions, I imagine there is sufficient reason to get just a little annoyed, especially when the ATC has said nothing wrt speed control.
When an aircraft has to wait for at least 4 or 5 other transmissions before they get responded to, it is anoying when their next request is for the opposite runway !!!
When one gives a heading after clearly and slowly using the callsign and speaking (specifically) clearly, and the pilot (of the correct a/c) says Uuuh was that for us, heading 300 ? then yes, I get a little annoyed. When all those events happen in the space of 2 minutes, I tend to let rip with a sarcastic comment like "Yes, runway 30 will be available in about 4 hours time, where would you like to hold?"
It is wrong to be sarcastic and abrupt on the frequency, but we ARE all human. I try my best to be formal and polite, it is NOT ALWAYS POSSIBLE.