I have pressure washed bugs off of my grill, but it will take the dip off of anywhere you have an imperfection. when I was dipping said grill, I accidentally dropped water on a small area, and that one spot came off, as did a few spots where rocks had actually pierced the dip. I touched it up after careful peeling/washing/drying, and it's still holding up almost a year later.
I remember someone posting what to use to wash off bugs but can't remember what it was.
soap and water should work, just be gentle.
Just did my rims this past weekend. Make sure you use a stripper to take the factory clear coat off, then wash with soap and water. We also used a primer before hand. TIP: use index cards between your rim and tire and you won't get the over spray.
I shot mine directly over the clear coat in case I got tired of it later. I did clean them good and then wiped them down with alcohol. Index cards work great. I tried masking one tire but the cards were easier and quicker.
Finally took the plunge and dipped my wheels. Love the new look. Didn't have a jack or lift to use so I did the wheels on the vehicle. Cleaned them really well first off. I didn't want to take a chance on dip on my tires so I tried the card trick first. For whatever reason some of the cards would not stick in around my wheel so I found something better. While reading some on the dipyourcar forums a guy told about buying a roll of Carpet Shield at Home Depot. Its a clear plastic that has adhesive on the back. A 100 foot roll was only $11 and change. Just unroll it on your tire, take a razor blade and cut the wheel out and you're ready to dip. Also another trick for painting on the vehicle is to take a trash bag, cut a slit down the middle of it, then stuff it in the holes of the wheel to cover the brake rotor. Works very well and you can wrap it around the rotor with ease. The hardest part of the whole job for me was taping up the lug nuts. Make sure you get 5-6 coats on the wheel. Downside of doing it on the vehicle is not being able to see the bottom part as well so make sure you get it covered good.