I have had AARP on and off for three years. I have never ever been able to use none of the discounts in those three years.
Everytime I've cancelled my membership they make false promises of big discounts on hotels, cruises, airplane tickets, concerts,etc, to lure you back to them. When you try to use the discounts they come up with different bogus excuses of why you can't use them. For example I booked a cruise and when I tried to get the discount AARP says the discount cannot be applied to that particular cruise. We tried again the following year, but used a different cruise line and got the same excuse.
I booked a hotel for a couple of days and AARP first said they saw no record of the reservation.
I told them that I have a confirmation of the reservation. Then they said they cannot apply the discount because the room was booked online.