One thing of note here is that on rare occasions a jingle has not been created by a professional, the story goes that a certain food manufacturer put out a competition which resulted in some housewife somewhere writing "A million housewives every day, pick up a tin of beans and say---" Though I doubt the same housewife also wrote the music that backed it.

That now brings me to another point that some jingles aren't musical and are just a catch phrase really, I think everyone will know where "It does exactly what it says on the tin" came from.

However in both cases they are memorable, in the first instance a catchy and very simple rhyming verse, in the second, it combines what is common sense, with the element of truth about the product!

I wonder how far you could get with a fictional hearing improvement product!
How does "Stuarts ear oil, the lubrication of sound" grab your attention eh?