(And don't get me started on the PETA billboard near my house that uses Reagan's picture and uses his Alzheimer's in a smear against eating meat...though I've thought about defacing that one myself.)
In Illinois, our large cardboard Bush signs are being vandalized by spray paint. My next door neighbor used WD-40 to remove the red paint. It worked! He used a cloth covered sponge to get into the grooves. He also used soap and water to rinse off the WD-40. Next time, we might used a spray bottle filled with soap and water.
Don't be upset. Get even! Tag back! When our corner sign got hit, I placed a small American flag with a yellow ribbon and a Bush sticker attached to it...plucked it right into the ground! If the runts come back...I got more!
Someone suggested hiding out with a paintball gun. Tag back can be fun.