I know this has been talked about a lot in marketing circles but I need to say it myself.
Is there anything more annoying on this planet that radio advertisements? Anything?
I was just down the street at the coffee shop and they were tuned into some hip hop station. They went to commercial and, WOW, did they start playing some annoying ads. I almost got up and left. Literally, one ad was nothing more than a man snoring really loud and a woman screaming at him. I don't know what they were selling -- mattresses I think -- but just on principal I would never buy anything from that company. They almost ruined my day.
It's not too hard to understand why they have to be so annoying; radio is an interruption-based marketing channel that, unlike TV and email, doesn't have access to your eyes. To compensate, they use intensity and volume which, when combined, can easily lead to bad things.
Think about your most profitable customers for a moment. Think back to before they knew who you were -- before they became loyal, before you loved and respected them. If you had 30 seconds to talk to them to them back then, what would you say? What would it sound like?