Perhaps the central cause of most failures comes not from thinking viewers will find it hilarious seeing white men dance badly (bad dancing has replaced the one-eyebrow-raise as the sure-fire laugh-getter that no one laughs at) but rather the underlying belief that the product or service you're advertising is a complete commodity.
A commodity to such a point that there's nothing important to say about the product or service, so let's not even try.
The Avis ads I've pasted above are a case in point. Avis apparently rents cars that have both radios (always magically tuned to a song you like) and space inside them. Those attributes appeal, of course, to busy businessmen who will suddenly break into song in their own private Malibus.
I'm sure some pea-brain of a MBA, on either the client or agency side, said something like this to the creative team: "Our insight is that the space inside a rental car is a private zone where our target can get himself ready for the challenges that come."
That's an insight on par with this one. On hot summer days fat people like ice cream.
50 years ago Avis developed an ethos to differentiate itself from a bigger, richer, more-established brand. We try harder.
Today the company and its agency is run by cowards who rather than try to do something smart, something unique, something ownable they instead write un-believable drivel acted by un-real people.
99 times out of 100 you advertise something that has no differentiating assets. Your job as marketing practitioner is to find one. A creed. A fact. An idea.
It's not just to cast for white people dancing.