Recently medical bills ruined my credit, so I can't qualify for loans.

The other methods such as asking the tenant for a rent increase or asking them leave to let you carry out renovation in the apartment may work but it will be a laborious task especially if they want to exercise their right and if it fails i mean if the tenant didn't agree or consent to your rent increase offer or renovation plan, it will ruin your chances of exercising your right as the owner of the property to use owner occupancy. 

If a pet ruins the carpet you can get reimbursed the remainder of the useful life.

However, I do not want to ruin the relationship by flat out telling him that I do not want to rent to him. 

There’s also the issue that it ruins your view.

Unless you have an end buyer in mind when you go to tie it up, you're wasting everyones times and further ruining the reputation of wholesalers 

If you plan to manage the property yourself, you've likely got a prohibited transaction that can ruin your IRA's preferential tax treatment. 

There were other impacts too - gambling addictions, ruined marriages, crime, etc.

The listing agent told me that the seller was a very difficult person to reason with, even for him, and that the seller's wife had  just been diagnosed with stage 4 cancer. 

That large "make-ready" invariably comes due at the absolute worst possible time (like all deferred maintenance) and ruins your numbers for the year.