Google Search trick?

I am finding in some sites that are pushing drug sales the cramming on
the site words which show up on a search but have nothing to do with
medicatio.

I have seen word cramming (for the sake of a better word) on porn
sites with the background black and the type black. Obviously this is
no visable to the usual surfer unless they do copy/past to another
document. Then it appears.

Is google screening out these words on non porn sites that are not
visable.

In my photography site I am thinking of putting competiters name as
well as caters which would then point to my site as well as the caters
site.

Any experience on this?