Desk research against primary sources, with the issuing authority linked where a page states an official fee, rule or deadline.
Because the peg has held since 1997, prices quoted in dirhams do not carry the exchange-rate uncertainty a floating currency would, which is why hotels and tour operators can publish AED prices well in advance without needing to adjust them for currency movement. That stability is also why converting prices back to your home currency in your head is a reliable enough shortcut for a whole trip, not just for the day you check the rate.
The fixed rate only protects you if you are actually being charged in dirhams — a business quoting a price in dollars or euros is applying its own conversion, not the peg, which is the entire reason that route tends to cost more. Ask for the bill in AED by default, and treat any price already given to you in a foreign currency as a number to double-check rather than accept.