Analogies are great. You take a concept that anyone can relate to, and use it to explain something unfamiliar. But you can push it too far.

• An analogy that is complex in its own right defeats the purpose
• An analogy that only partly fits
• An analogy for which you cannot find the appropriate professional visuals easily without an advance degree in Photoshop
• An analogy that is number 12 in a series of completely unrelated analogies for every single concept in your presentation
• An analogy that is not "serious", it undermines the professionalism of your presentation, a bit of humour is OK, college humour is not.
• An analogy that is a cliche

Or, like in the Accenture ad below, you are actually insulting your target group.

Good analogies are pretty much the opposite of the above. They are simple, fit the subject, are easy to visualise, and ideally, can cover all aspects of your story.