I use what works- for me. It may be a commercial bait; it may come from the grocery store; it may be something of my own formulation; or, it may be no bait at all. Some peanut butter, sunflower seeds, oatmeal, (maybe some nut oil) and food coloring mixed together and put into a non-labeled (or computer generated labeled) jar will work for many species of rodents. However, I probably do more "no-bait" cage trapping than I do using baits or lures.
I don't have any woodchucks in my area. I understand that many folks recommend various fresh vegetables to catch them though. I would think that it is difficult to disguise broccoli, cabbage, clover, etc. Yes, there are commercial baits available, but do they work better? Other folks use body catch traps (with no bait); still others use unbaited cage traps.
I have very few skunks here too. If using bait, a chicken or fish based bait is hard to beat. Again, I seldom use bait for skunks. Problem skunks, around here, are found under homes. If they went under, they have to come out. I close all potential entrances except the main one. The setup only allows one way out- into the trap(s).
I have heard though, that the best skunk set-up is make the best coyote, bobcat, or fox setup that you can. Use the most expensive bait or lure. Use absolutely scent free procedures. Leave no indication that a human has ever passed that area. In the morning you should have a skunk or opossum.
Ron Fry