I'm unsure of how they're handled with humans (I'm surrounded by a Smash dead zone and don't have high speed Internet), but some CPUs just inspire me to wrath. Olimar is CHEAP. He keeps spamming his fair, fsmash, usmash, and uair, which basically blocks every possible attack with a disjointed hitbox. Pikachu is also a cheap arsed CPU: even on level nine, he just spams his up and down smashes, his Thunder, and his Thunder Jolt. It's especially annoying since Thunder was buffed so much. Diddy Kong is also rather cheap, for some reason. Jiggly's not cheap, just annoying. Meta-Knight is a pain, simply because his attacks come out so quickly and have next to no ending lag. Snake isn't bad as a CPU, but noob human players find a quiet area of the stage and start spamming his Nikita: THAT gets obnoxious pretty quickly. In four-player matches, I usually go Snake hunting as a first priority.
Some characters, on the other hand, I just feel sorry for. Link, Samus, Ganondorf, and Captain Falcon all try really hard. They try. But it's PATHETIC.
And Captain Falcon is far from honorable. If you zoom in on his up-B in slow motion, you can clearly see that he uses the technique to **** his opponents with repeated pelvic thrusts. Not very nice.