For soap scum removal I've never found anything that works better than Dawn Dishwashing Liquid. A little bit on a wet rag is all it takes. For shower doors, follow with a rinse and a quick swipe of a squeegee (you can find one at the dollar store). For everything else just rinse and wipe dry.
don't use dawn on a regular basis on your car. If you do be sure to wax after as it removes any wax that was already on the surface. It pulls out all of the important oils on your paint causing it to dry out and eventually flake off.
Login using the form on the top of the page to post feedback (if you are a registered user). If you have not yet registered, click here to do so. It's FREE!.