Kind of a vague question. If you wash your car with dish soap, yes the alkalines within it can adversely affect your paint. I use a Zymol auto wash (there are many good ones out there), wash my car twice a week, and have no problems. I would recomend a good few coats of wax (annually) and a spray detailer after washing so that the finish remains protected.
On the flip side, washing your car too little can also be harmful. Those of you in winter climates that drive on salted roads can certainly be harmful to your paint (and other areas of the car) if not washed frequently.