Can you give an example of a marketing campaign that did not work out as planned?

There are many failed marketing/ad campaigns that did not work out as planned.
The main reasons behind such failures were most of the time a lack of understanding of consumers' psychographics, and a lack of planning.
For example, in an attempt to earn celebrity endorsements to help gain more interest from consumers, Reebok decided to recruit 50 Cent (the rapper) to be their endorser.
But Reebok’s marketing team wasn’t portraying their message clearly, and the ad only discussed how 50 Cent had been shot nine times, with zero mention of Reebok.
After consumers complained that ads promoted violence, Reebok eventually pulled them.

The failed campaign may be because a weakness of a market study, Or some missing points.
I haven't experienced that before.

I agree with Reem.
So many campaigns may look shiny and coherent on the outside, but their pillars -research, research, research- aren't and that leads to the eventual failure of the campaigns.

I do believe that a lot of marketing campaigns fail for several reasons:
1- Segmentation.
no clear segmentation of who the client is, whom we need to target.

2- Image.
How does the overall image look like.

3- Channel.
What communication mean should be used.
Any campaign should be designed from day one with consideration to the 3 steps above to have a successful ROI campaign.
As said 50% of campaign investment is go to waste.