I'm very surprised by all the cat hate here! It sounds like lots of experiences must have been with horrible owners. As any animal they will resort to awful things if you treat them awfully.. I'm sure if I didn't give my cat food he would hunt for it (occassionaly he tries to drink water from weird places if I didn't realize his waterbowl got low) and he would probably poop and piss everywhere if I didn't give him a litterbox. No different for a dog!
However my cat is very clean, and I've owned many cats over the years. There's really no "training" for a cat- they instinctively know how to use a litter box. The only thing I've trained him to do is not go up on the counter and tear up the furniture, and that took a couple months and a couple couch covers. I guarantee you can not smell "cat" in my home unless it's within a couple minutes of him using his litter box, which I keep near window to air out quickly. My shit stinks too when I use the toilet. Puking only happens if you change their diet, overfeed them, or they have some kind of intestinal problems. Hairballs are avoidable if you groom your cat or if you get a breed that has short hair.
I'll go on multiple day trips and set up his autofeeder and when I come back everything is just as I left it. And I think this is the same for any well kept, fixed cat. There really is little maintenance involved. He lets me know when someone pulls up to the driveway, he will chase after any intruding pests or bugs, and he's just a fun little dude. He'll even play fetch:
http://www.youtube.com/watch?v=XPBKpaaMsnw He does have a lot of energy, so if I don't let him out in the yard on a harness or play with him once in a while he will run around the house like crazy, but never causing any damage.