I don't really use a QD as a cleaning agent for the most part, but as others have said to enhance the appearance and feel of the paint. And I find the anti-static properties (I use 425) also helps a lot in keeping the dust away from the paint (and especially the glass) in the first place.
All I know is that after I wash the car, it doesn't feel quite as slick, nor look quite as shiny as it did until I use the QD, which is why I use it each and every time as a true LSP.
All I know is that after I wash the car, it doesn't feel quite as slick, nor look quite as shiny as it did until I use the QD, which is why I use it each and every time as a true LSP.