When using ini_set() on a non-configurable setting, it'll return a "non-existent" local value.  For example, I run this while magic_quotes_gpc are globally on :

    if (get_magic_quotes_gpc() == TRUE) {
        ini_set('magic_quotes_gpc','off');
    }

    if (get_magic_quotes_gpc() == FALSE) {
        print 'magic_quotes are off';
    } else {
        print 'magic_quotes are still on silly';
    }

It will print 'magic_quotes are off' when really they are not.  Admittedly this aspect is 'out of my field' but after a php-general list posting I am told :

"Directives that affect actions that are taken before a script is parsed, such as mangling EGPCS data, can not be changed by the script."  -- Rasmus

Which makes sense but it seems the attempt above should not "partially work."  phpinfo says :

    magic_quotes_gpc : localvalue = off , mastervalue = on

When I assume there is no such thing as a local value for these type of directives, right?  Something is up.