we say silicone,but really mean any grease/oil that might contaminate..
sikkens do a anti silicone flow out and does work well but you have to use it carefully as it flows out real easy
the dots that appear in paint work that are often refered to as fish eye are only caused by silicone.
and you can buy silicone drops an aditive to put in whatever paint your using so that the silicone on the car has nothing to react with as the mix already contains it.
the only problem with this is you dont know that you need it until you have applied your first coat.