Raccoons definitely do get smart to the traps if they have the opportunity to get caught in one more than once! That's the problem with the cash and release crowd: they are just creating new super raccoons that have experienced the traps and therefore know to avoid them.
I had a horrible raccoon problem in my shop, they were just destroying everything. I talked to him more experience Hunter at the start, and he assured me that I definitely had more than one or two raccoon. I got a live trap which I bait with whatever leftovers are in the fridge, and before the problem was resolved I went through over 30 raccoon!
The bottom line is you need to trap them and kill them, there really is no other way.
If you live in one of those pus sy towns where you can't shoot them, there are other ways.
I have never done anything but shoot them, a 22 hollow point shot to the Head is quick and humane. I've heard people recommend dropping the live trap in a barrel of water to drown them, but I've heard many more people report that that is a slow and inhumane death, and I have heard of people being charged by The Humane Society for doing that.
If I wasn't able to shoot, the other method I have heard of is to construct a gas box. Just make a small plywood box just a little bit bigger than your live trap, put a door on one end, and a hose intake on the other end that can connect easily to your car's exhaust. Slide the live trap in, close the door, connected to your car, and run the motor for a little bit. There are plenty of instructions on the internet that tell you how to do this in more detail. I've never done it, but everything I have heard says that it is a nice Humane death for the raccoon, as unlike drowning, they do not sense that there's anything wrong, they just quietly go to sleep and don't wake up.
Good luck, but just be prepared, because odds are you have a more serious raccoon problem than you realize.