John Carpenter failed The Filmmaker's Exam at question 1 when he cast Rowdy Roddy Piper in the lead role of They Live. However, the movie itself was so painfully bad that even if Carpenter had somehow gotten Harrison Ford or some other luminary to act in this movie, it still would have sucked.
Hot Rod really isn't a bad actor, he's simply not a very versatile actor. Piper prepared for his acting career by being a professional wrestler. As such, he learned how to express two emotions very well -- "In Pain" and "Not In Pain." Unfortunately, he never expanded his repertoire of emotions to include such vital ones as "happy," "sad," or "angry" -- any one of which might have helped him at some point in this movie.
This movie has a slow buildup for what is essentially an action movie. At least I think it has a slow buildup. I watched it on TNT's Monstervision, so I'm not sure if the first part of the movie was slow or if TNT just had more commercial breaks than usual to pad out the running time of the show. Anyway, this buildup requires Piper's character to stand around looking perplexed a lot. Of course, since Piper can't act "perplexed", he instead spends most of the first half hour with a very placid, serene expression on his face, which I can only assume is his "Not In Pain" expression. It's completely out of place in this movie, however.
Eventually, the pace picks up, and Piper starts killing things. He also gets hurt, so we get to see the full range of his acting talents. Piper has some of the most memorable lines in B-movie history (most of which he ad-libbed himself, at John Carpenter's request), but this isn't enough to really make this movie watchable. Even the amazingly dumb, painfully long (clocking in at 7 1/2 minutes screen time, with another five minutes cut) fist fight can't provide enough laughs to make this movie fun.
I think the worst part about this movie is that John Carpenter apparently made it as a statement against Reaganomics. What zombies from another dimension have to do with Reaganomics only Carpenter knows.
Scene to watch for: The fist fight
Best line: "I'm here to chew bubble gum and kick @$$. And I'm all out of bubble gum."
Things that make you go "Huh?": Piper's laugh during the fist fight.