Paint Surface Analysis Test
Having washed and dried your cars paintwork, you can perform a paint surface analysis test.
Run the back of your hand over one of the cars painted panels and you should feel a smooth glass-like surface. If you feel any minor bumps or cannot glide your hand easily over the surface then you may be feeling contaminants on the surface.
If you believe contaminants to be bonded to the paintwork after washing then I suggest you clean you car's paintwork using either the clay detailing system or a similar alternative.