Several people have said CC used to make very good knives, and indeed they did. They were the meat industry standard for generations. However, the name was bought by another company which has, for the last 20 years or so, made very bad cutlery indeed. As good knives go, they aren't good knives -- they're junk. But, so what? If you like your Chicago Cutlery knives and want to keep them, then that's what matters most.
That said all dull knives are pretty much equal. If your knife isn't very sharp, it really doesn't make any difference how "good," expensive, or prestigious it is. And that goes double for anyone who disapproves of you knives. Triple even. If you don't sharpen regularly (and properly), don't maintain the edge between sharpenings, don't use a wood or "Sani-Tuff" type board, and don't store your knives properly in a block, a drawer block, a mag-bar or individual blade covers, then it's almost certain your knives aren't sharp.
Not that you should do all that stuff. I'm not preaching or judging, or saying you can't be a good cook without wonder-knives made by Japanese gnomes from Swedish steel and maintained by German elves with Arkansas stones -- like I do. I'm saying if you don't take good care of your knives, then the CC is as good as anything else. Chances are you do a lot of cutting with a steak knife or a bread knife anyway. So do a lot of people. Most, in fact.
If you're not into knives at all (or if money is a big issue right now), and you want to make those CCs useful, I'd suggest getting a type of sharpener called a "Mini-Chantry." They're made in England, are good looking, safe, easy to use (no learning curve at all), easy to store, well-made and reasonably priced. The Chantry replaces both sharpening and steeling. The feel your knives will have after using it is like a very sharp, very fine-toothed saw. Chantry sharpened knives will definitely cut through tomato, onion, or anything else you care to cut, easily. Here's a link: Chantry Mini Chantry Knife Sharpener: Black - Chantry Knife Sharpeners
It's a good edge for your CC and other similar inexpensive knives made with steel too grainy to take a fine edge, and both too brittle and too soft to hold it. However, I don't recommend a Chantry for a more expensive knife.
You can take rust stains off your knives with "Scotch-Brite" pads. Those are the rough green nylon things which fall somewhere between pad and cloth. If the stains don't come right off, try a little baking soda on the pad. It's better to prevent the rust then to treat it, though. Try and rinse and dry them as soon as possible after cooking. Don't let them sit on the counter, soak in a sink, or air-dry in the drain rack overnight; and never clean them in the dishwasher.
Full disclosure: Actually, almost all my knives are antique, vintage or just plain old carbon steel Sabatiers. They all may be sharp, but none are shiny. I'm old, not shiny and not all that sharp either.