The 10 things that kill deals, and none of them are what new investors think

I've walked a lot of properties over the years (30 years in construction/inspection), and the deals that actually blow up are almost never the obvious stuff. New investors worry about paint and countertops. The deals that lose money die from:

1. -Bids that look complete but aren't, contractors write bids to win the job, not to disclose the full scope
2. -Roof age that's a guess, not a fact, no documentation, no permit, just "the seller said"
3. -HVAC systems running past their useful life while "working fine"
4. -Foundation patches mistaken for foundation repairs
5. -Electrical panels (Federal Pacific, Zinsco) that insurers won't touch
6. -Work done without permits, which means work that was never inspected
7. -Deferred maintenance that compounds, a $500 gutter fix ignored becomes a $15,000 roof deck replacement
8. -Change orders that surface after you've already committed
9. -Environmental history nobody mentioned (former dry cleaners, gas stations, etc.)
10. -The deal you talked yourself into because you wanted it to work

Curious what this community would add, what's the one that's bitten you personally, or one you caught right before it cost you?