If you have a bit of automotive clay, or a clay mitt, after washing try the clay on a leaf stain.
I haven't had to deal with leaf stains but clay does seem to remove other stains such as old bird poo, water stains, and tar stains. Clay mitt seems to work too.
Clay should be less aggressive than polish. As long as most of the grainy dirt is washed off first.
I used this stuff.
http://www.cleanyourcar.co.uk/detail...prod_1163.html
and this
http://www.halfords.com/motoring/car...prep-clay-mitt
Although the Bilt Hamber medium clay is better than mitt at removing really stubborn stuff like old tar stains on the lower body.
So far I have not noticed any claying-induced scratches, just go very light no pressure and always over wet panels.