How do I determine poor performance vs poor management/accounting

[Ali Kassam]

I'm under contract to purchase a 41 unit POH MHP and a 24 machine laundromat.  24 of the units are currently rented.  When I originally met with the owner, it was obvious that he wasn't going to have great records.  Most of his record keeping was all paper files.  As I've been doing my due diligence, I can't tell if this is just a matter of the owner practicing poor accounting principles, or if I should run away from this deal.  I've been to the property and can verify the occupancy.  

Red Flags

1. The rent roll totals to about $144k/yr, but on his 2020 tax return he only shows $70k worth of rent collected.  This same thing applies to 2019.
2. His profit/loss on his returns for 2020 and 2019 both show a 25k loss with over $100k in expenses
3. It's a coin operated laundry, but the 2019 and 2020 taxes don't show any laundry income
4. The laundromat has been closed for the last 9 months supposedly, but it has 0 reviews online.  In comparison, the laundromat 1 mile away has 31 reviews on Google. 
5. Every lease states rent is due on the 1st of the month.  When I asked for proof of deposit for December rent roughly $4k was deposited on Dec. 7th and $8k was deposited on Dec. 17th.  

Is it that out of the ordinary for an owner to under report 50-75% of their income?  Would that be a huge deal breaker, or just cause for concern?  

I look at this deal as a big value add opportunity by renovating the 17 vacants, so if this is just bad accounting, I'm confident I can turn the property around.