Rarely does an advertiser write a better ad than an advertising agency would write for him. Usually they're boring, sometimes pathetic, and sometimes you just scratch your head and say, "huh?"
The worst are the ones that draw on some song or TV show from 40 years ago that was a favorite of the business owner.
For example, there was an ad running for a month or so that mimicked an exchange between Ralph Cramden and Ed Norton from "The Honeymooners". Aside from the ad being hamstrung by very poor impressions of Cramden and Norton by the actors, there's the issue of demographics. Probably two-thirds or more of the listening audience had never seen or heard "The Honeymooners", and so probably didn't know what the ad was intended to mimic, or that it was in fact mimicking anything.
Back in the early 1970's or late 1960's, there was a comedian (and I use the term loosely) who appeared a couple of times on The Tonight Show. It may have even been earlier, on the Ed Sullivan Show. At any rate, his schtick went something like this: [sad-sounding violin music] "You say you want to pull yourself up by your bootstraps, but you don't even have any boots? Is that your problem, bunky? [marching band music] Well, hold your head up high!...", and so on. It was horrible. The "comedian" had about six minutes of fame.
That didn't stop some business owner from using a very bad impersonator to do an ad in that style. I suspect the business owner wrote the ad himself. I felt embarrassed for the employee who had to drop the tape off at the radio station.
Today I heard an ad for an insurance agency. The ad's theme song was "insurance agent man", done in the style of Johnny Rivers' "Secret Agent Man". I would guess that a third of the listening audience had ever heard "Secret Agent Man". I'd also guess that another third or so who had heard the song wouldn't remember it. And I'd guess that some portion of the last third hated the song so much they'd never use the insurance agent, just because of the song.
Advertising copywriters don't try to sell insurance. Why do insurance agents (or other types of business owners) think they can write copy?