The 7 Deadly Sins of PowerPoint Design (And Why Your Slides Are Killing Your Credibility)

Your slides are killing your credibility before you even speak. I don’t say this to be provocative — it’s something I’ve observed consistently over 16 years of presentation design work. Audiences form judgments about a presenter within the first moments of a deck appearing on screen. A slide that signals poor design choices doesn’t just look bad; it creates a credibility gap that the presenter then has to overcome through the quality of their delivery alone.

Most of these problems are fixable. But first you have to recognise them. Here are the seven design mistakes I see most consistently — what I think of as the 7 Deadly Sins of PowerPoint design.

The 7 Deadly Sins of PowerPoint Design

Sin 1: The Wall of Text. Bullet-heavy slides force audiences into an impossible choice: read the slide or listen to the presenter. The brain processes written and spoken language using overlapping cognitive resources — when both compete simultaneously, comprehension suffers for both. The 6×6 rule (no more than six words per bullet, six bullets per slide) is well-intentioned but not the right frame. The right frame is: what does this slide need to establish, and what’s the minimum content needed to establish it? Start from there and work down, not from a template and work up.

Sin 2: Visual Chaos. Inconsistent design across slides — different fonts, misaligned elements, varying colour treatments for the same type of information — signals disorganisation at a subconscious level before the audience has processed a single word. Consistency isn’t just aesthetic; it’s cognitive. When the design is consistent, audiences spend zero effort on orientation and all their attention on content.

Sin 3: Animation Overload. Animations that exist to demonstrate PowerPoint capability rather than to support the argument are always a mistake. Flying text, rotating graphics, and spinning transitions create awkward pauses and direct attention to the wrong thing. Animation has legitimate uses — revealing information in a deliberate sequence, showing a process moving through stages — but the default should always be no animation, with deliberate additions where they genuinely serve the communication.

Sin 4: Unreadable Visuals. Charts that require close reading to extract the point, data tables that are legible on a laptop but disappear on a projector screen, images that are pixelated or poorly cropped — these are all versions of the same problem: the visual is doing the opposite of what visuals are for. Every visual element should communicate faster than the equivalent text. If it doesn’t, the text is better.

Sin 5: Poor Colour and Contrast. Colour used decoratively rather than meaningfully creates visual noise. Colour used in violation of contrast ratios creates illegibility. The two most common specific mistakes: using colour to make slides more interesting (which it doesn’t) rather than to signal information categories (which it can), and insufficient contrast between text and background that makes slides unreadable in bright rooms.

Sin 6: Unstructured Layouts. Slides where elements are placed by feel rather than by a consistent grid look amateurish even when the individual elements are well-designed. The eye needs invisible structure — consistent margins, alignment, and spacing — to process information efficiently. Without it, even good content feels chaotic.

Sin 7: Irrelevant or Low-Quality Imagery. Stock photographs of people shaking hands, generic cityscapes as section dividers, or images that illustrate a word rather than making an argument — these are visual noise. Every image should either explain something that’s harder to explain in text, or create a feeling that the text alone wouldn’t produce. Everything else should be removed.

The Fixes That Actually Matter

Addressing these sins doesn’t require a complete redesign. It requires a set of commitments: one typeface family with clear weight distinctions; a defined colour palette where each colour has a specific meaning; a grid that determines where every element lives; a rule that every slide communicates one thing clearly rather than several things approximately; and a default of no animations unless there’s a specific reason.

The common thread is that each sin is a consequence of optimising for the wrong thing — for comprehensiveness over clarity, for visual interest over visual logic, for demonstrating effort over enabling comprehension. Good PowerPoint design doesn’t try to make slides impressive. It tries to make the argument they carry land as efficiently as possible.

If you recognise more than two or three of these sins in your current decks, it’s worth addressing them systematically rather than slide by slide. See also: how to simplify complex slides without losing the point.

If you’d like a direct assessment of where your presentations stand, I’d be happy to take a look — get in touch at depicts.com/get-started.