I do, it doesn't harm to try. Branded items have Un announced discounts. Like Dior for example, I got 20% off Dior shoes. They didn't have a sale but when when i asked for it they gave it to me, I also bought 4 watches that were on 50% discount. I liked a pair of sunglasses that wasn't on offer, but when I asked for a discount, they gave me 15% management discount in addition to two free branded key rings & a free Perfume as I spent a huge amount of the watches.
I ask for discount when I buy jewelry, watches, branded shoes & handbags & I always get a discount or a free gift.
I also ask for a discount from small furniture shops (not chain shops), insurance (so good at it, I contact several companies & I keep sending the quotes to all of them until I get the best price), if they can't give me more discounts, they offer me more benefits like free rent a car, lower excess, breakdown roads assistance, etc. I go with the best package I receive.
When I book a hotel room, if I can't get any discount, I ask for a confirmed late checkout before booking.
When we bought our car (agency car) I spent over 2 hours negotiating the price, I got a good one with a life warranty as long as I own the car & a free insurance.