toothpaste spit all over the bathroom faucets, and some sort of substance -- guessing food smeared all over the bathroom counter.

even if they did, likley no harm at least as I see it.Take the booking and get a great review, pocket the cash and move on. 

Are there trees over the house that could harm to house?

In my opinion if I did something that caused legitimate harm to someone else then I would be at the very least morally obligated to make the situation 'right'. 

People can get harmed and killed anywhere, it just bothers me how he told me all these things right before a deal was in the works. - If you invest into Florida, what are your tips for staying safe as a “landlord” or just in general?

As long as you disclose everything, you should have no problems.In my opinion, a real estate license is helpful instead of harmful.

I personally don't see the harm in getting positive cash flow even if it's smaller because at the end of the day it's still paying down the mortgage.

If it fails then you back out no harm no foul.That may seem unfair to the seller, but it might also result in them being able to sell for a higher price than they could have otherwise.

Donald Cressey is The Fraud Triangle: 1- A perceived unshareable financial need. 2- Perceived opportunity. 3- Rationalization.Financial pressures change in life, medical care for aging parents, a family member becomes ill, college costs, mid-life crisis, substance addictions and gambling, jealousy/feeling "owed" or wronged, social pressures to "get ahead"...The biggest losses are always where there are no checks & balances, no separation of duties, no policies and procedures in place. 

I'm thinking that there wouldn't be any harm besides maybe following up too much with them if I did both at the same time.