Assertive is good, it's a pleasure listening to a good approach controller doing his job, along the same lines, most experienced ATCO's can tell by response time, RT phraseology etc. whether or not a pilot is experienced or not and will take that into consideration. An assertive controller will get better cooperation from pilot's IMHO. I once worked with an assertive controller that saved the day years ago when she noticed a faint target behind the a/c on a PAR approach, she immediately checked the flight schedule and confirmed it was the banner tow aircraft with 2000 ft of banner, great save!