This is for WordPress Plugin and Theme developers. Don't read further if you are not one of them.

To get an extra argument in your filter (say for a 'bloginfo' filter) you have to specify not 2 but actually 4 as number of arguments in add_filter (read below for details). The returned data are: first argument, filter name, first argument, second argument

BTW: One place where this function is needed is for writing 'bloginfo' filter. It passes two arguments - value and key.

So when I add_filter I have to write:
add_filter('bloginfo', 'my_filter',10, 4 );
10 is the priority
4 is the argument count

And then I access the second argument as:
function remove_css($first_argument,$dummy,$dummy,$second_argument)

I haven't tried for more than 2 arguments but I suspect it will be equally funky. I have reopened ticket 901 and update the comments.