You found a startup that looks promising. The pitch was sharp, the founder was charismatic, and the market sounds huge. But before you write that check, there are warning signs that even experienced investors sometimes miss.
Here are 7 red flags we see regularly when reviewing startups for our clients.
1. Founders with gaps in their professional history
Everyone has career transitions. But when a founder's LinkedIn has unexplained multi-year gaps, or their claimed experience doesn't match public records, it's worth digging deeper.
We've seen founders claim "CTO at a YC startup" when they were actually a junior contractor for three months. This doesn't mean the person is dishonest - but it does mean you should verify before trusting the narrative.
What to check: LinkedIn history, public company records, mutual connections who can confirm roles and tenure.
2. Financial projections that don't connect to reality
A startup projecting $50M ARR in year three with no paying customers today isn't optimistic - it's disconnected. The problem isn't ambition. The problem is when the model has no grounding in actual unit economics.
Look for these signs:
- Customer acquisition cost (CAC) that assumes viral growth with zero marketing spend
- Revenue projections that assume 100% annual retention from day one
- Gross margins that ignore infrastructure, support, and compliance costs
What to check: Ask the founder to walk you through the assumptions behind three specific numbers in their model. If they can't explain them clearly, that tells you something.
3. A pitch deck that avoids the competition slide
Every startup has competition. If the pitch deck skips the competitive landscape entirely, or shows a magic quadrant where they're alone in the top-right corner, the founder either hasn't done the research or is hoping you won't.
The best founders know their competitors well. They can articulate exactly where they differ and why that matters for their specific customer segment.
What to check: Search for alternatives yourself. If you find five competitors the founder never mentioned, ask why.
4. Code repositories with no tests and no documentation
If you're investing in a tech startup, the codebase matters. A repo with zero test coverage, no README, and commit messages like "fix stuff" tells you something about engineering discipline.
This doesn't mean the code needs to be perfect. Early-stage code is messy by nature. But a complete absence of testing and documentation suggests the team is moving fast without any safety net. That's a risk that compounds over time.
What to check: Ask for read-only access to the repository. Look at test coverage, commit history, and whether the architecture is documented anywhere.
5. A go-to-market plan that's just "we'll do content marketing"
Content marketing works. But when the entire GTM strategy is a blog and some LinkedIn posts with no paid acquisition plan, no partnerships, and no sales motion, you're looking at a startup that hasn't figured out distribution yet.
The best GTM plans are specific. They name the first 10 customers they're going after. They explain the sales cycle. They have a realistic timeline for when revenue starts.
What to check: Ask the founder to describe their last 5 customer conversations. If they can't, distribution is still theoretical.
6. Data room documents that are incomplete or inconsistent
When a startup provides a data room with missing cap table details, unsigned agreements, or financials that don't match the pitch deck numbers, it raises questions about operational rigor.
Common issues we see:
- Cap tables that don't account for all issued shares
- SAFE notes or convertible instruments with unclear terms
- IP assignments that were never properly executed
- Employment agreements with non-standard clauses
What to check: Cross-reference the cap table with all fundraising instruments. Make sure IP is properly assigned to the company, not the founders personally.
7. Resistance to the diligence process itself
This is subtle but important. If a founder pushes back on basic diligence requests - not because they're busy, but because they seem uncomfortable with transparency - pay attention.
Good founders understand that due diligence protects both sides. They welcome the process because they know their business can withstand scrutiny.
What to watch for: Delayed responses without explanation, reluctance to share financial details, or pressure to "close quickly before the round fills up."
The common thread
Most of these red flags share a root cause: the startup hasn't been through a rigorous review before. They may not realize their financials don't add up, or that their code has issues, or that their data room is incomplete.
That's not necessarily a deal-breaker. But it is something you need to know before investing.
At Proof Diligence, we review startups across all six of these dimensions - founders, pitch deck, code, GTM, financials, and data room - so investors can make decisions based on verified information, not just a good presentation.
