Venture capitalist Roelof Botha argues that startups should take off the polish when pitching him:
MB: What puts you off when looking at a startup for possible investment?
RB: Unnecessary hyperbole and polish — I much prefer raw authenticity
At first reading, this might suggest to save yourself some time and stop investing in your investor presentation. But I think the opposite is true: good presentation design is actually all about taking off the polish and bringing the raw story out, rather than shining everything up.

Slides with bullet points in fluffy language full of buzz words are polished. Minimalistic, beautifully designed visuals are raw. And this applies to all types of presentations, not just investor pitches.