<p>It makes a difference. It definitely looks good on the app to take many AP's and get 4's/5's. Shows a love of learning (that the colleges like) and readiness to take college-level classes and succeed in them. Whereas if you didn't take a lot AP's, they'll know you didn't take a rigorous workload, or you weren't willing to challenge yourself. If you took an AP class but not the test (or you did bad, or you cancelled your scores), it'll show that you aren't committed to going the whole way. So yes, one bad AP score won't kill you, but several bad ones will. And several good ones will really, really help.</p>
<p>FWIW, last year's valedictorian at my school took 12 AP tests, got 5's on all of them, and was accepted to Harvard.</p>