Can't Vandalize Buildings/Can't Improve Righteousness

[2006cool]

A cant find no spray cans

[darrenhill760]

Add some training walls into your town - each one up's your righteousness rating.

[wadebear]

If you're looking for spray cans in your own town you're not going to find them - they appear in your neighbor's towns when you visit, but only if no one else has already tapped them.

As the other guy (gal?) said, buying Training Walls can help with your Righteousness.  I have 5 in my town and my Righteousness is almost always 5 stars.