Dubai is very overrated. I live there at the moment and while downtown and the marina are very very nice, those don't reflect the actual emirate at all. Dubai is mostly just fucking desert, and while it isn't shabby, most of the population is lower middle class and so it's just a very normal place, hurt by the fact it's in the middle of the desert.
Even the wealthy parts of Dubai can be very tacky, I don't really like the way many rich people flaunt wealth, I have always found it very distasteful. There also isn't a lot to do as a tourist or resident, so there's that.
Paris is super nice in some areas, and we have a nice history and some really good architecture. Problem is a lot of Paris is a shit hole, it's a dirty city, over run by tourists, and Parisians are some of the most annoying people in Europe.
If I think of cities I find overrated on the top of my head I would say Singapore is a boring place. Nicest imo are Kyoto in Japan and Hong Kong is a great place for the most part, ignoring glaring inequality issues and frequent pollution.