There is a long road from an idea to a finished product. It is a bit like construction, where it is left to the engineers to transform the ideas of architects into reality. Designers, too, might have phenomenal ideas, but sometimes materials, circumstance or just plain unprofessionalism might turn them into hilarious results.
That does not always have to be a bad thing, as great results are often born out of something undesired. A subreddit called “Crappy Designs” has gathered some of the best examples of designs which turned out not to be what designers envisaged, with tittering effects. Hee hee