Sorry man... I'm sure you have good reasons to question the validity of some of them and I don't doubt your sincerity. It was my understanding that they are all legitimate. I don't want to promote a 2nd year business student's work as an original pitch deck so I can look more closely into the provenance of problem slides if you could name these and I'll either redact them or adjust the title accordingly. Thanks for bringing this up :)

I just want to add my 2 cents in hope that it's helpful. I'm a co-founder/partner of a seed-stage VC fund and do keep track of the pitch decks we've seen as a partnership over the past two funds spanning six years.

Comparing these decks to the decks I have in our tracker (a dataset of similar size to yours), there's a lot of differences. Even if you only take the pitch decks of the successful companies (most of which we didn't invest in), a lot of these decks look a lot more polished.

Here's what I think is going on: Some decks are undoubtably real seed pitch decks, some decks are demo day decks from accelerators, and a few of these decks (Facebook's, for example) are after-the-fact business school exercises from students.

So, I do think most decks are real, but what's tripping up some people is how polished some of the decks are. True pitch decks used to get a seed round or into an accelerator aren't very polished because you're constantly changing the deck based on feedback over the span of 20-50 pitches. The truth is that many investors I know worry when they see a too-polished deck that everyone else has already seen the deal and passed :-P.