I don't think people are picky enough about their samples anymore. I like a very clean sample and will tinker until I get it. So many folks just set it at what a book says and don't account for wear or conditions. Folks with new machines just trust that machine to do things automatically. The days of adjusting a combine with a crescent wrench are over. At least for the folks running equipment newer than I do.
You can get a Gleaner to give you a nice sample. It just takes a while to learn your machine and crops. I really do think that machines from many years ago gave a so much cleaner sample with little waste. Our Massey Super 92 gave a beautiful sample - I haven't seen a load of grain that nice since it cut its last bin full.
Never had a Gleaner. I have heard over and over that they are a very user friendly machine. Give it time to learn that machine and you will pull in grain you can be proud of. More important than make of machine is the care it got before you bought it. Find some old boy in his 70's that took care of his machine and knows that machine like the back of his hand. You will have something you can run for 20 years easy regardless of the color of it.