How dangerous is this? 

And she was the ONLY tenant I have ever had who was a complete nightmare and came danger close to being evicted.

That is dangerous.  

However, there is a dangerous assumption that property prices will come up.

It is a very dangerous idea to hire kids to get involved.

Buy back options are very dangerous for you as the investor.

I, personally, always think it's a dangerous assumption to assume "bad management" or that the owner is selling because "they want out". 

you somehow figured out the market you are in is just on up and up ( first 6 months to a year of explosion) and you absolutely sure its only going to go up ( but stay away from turnkey companies, agents that use words like "cash flow cow" and  "guaranteed ROI in double digits"  because no one can guarantee you anything in this life... 

You can also ask the seller to renegotiate the price, but he isn't obligated to do so.Cash deals don't require an appraisal because there's no lender involved, but you can ask for and pay for one for your own purposes.BTW, this is the textbook definition of the dangers of buying the biggest, nicest, fanciest, and priciest house on the block.

Excessive upfront fees are dangerous for the borrower.