Over time, it is not unusual for automotive paint finishes to become slightly rough to the touch due to the gradual accumulation of various surface contaminants that are too firmly bonded to be removed by normal washing alone.
To determine whether your paint has acquired firmly bonded surface contaminants you should wash and rinse your car thoroughly and then run your fingertips over the wet panels. Clean paint should feel perfectly smooth, if you can feel rough spots or a gritty texture then unfortunately your paint is affected. Also, in some cases you may even be able to see such contamination upon close inspection, particularly in the case of tar spots and brake dust.
