I'm looking at a deal where the wholesaler is saying he cannot guarantee a clean title.

Seeing this everyday I'm sure was a factor in my friends' brothers' delilberate demise.The renters helped me clean and paint beginning a few days before finishing yesterday. 

“She’s the best tenant, so clean, blah blah”.

Even the cleaning service is paid by the guests.

Fill any holes they use to get in , bait traps outside , snap traps inside , clean up trash and debris around the house . 

Since I'm not a lawyer and I don't know what state you're in, you'll need to find out if this property passed to this guy automatically because a living trust was in place, or if it needs to go through probate before he gets it, or if he was a joint owner with the sister.If all this is clean, then you should be able to buy it from the guy.

Honestly you’re blowing smoke just come clean so you don’t ruin the rest of whatever credibility remains 

Because you described your tenants as "slob", I think you need to have a serious talk with them about maintaining the house clean and free of bugs.

Having someone change sheets, clean, organize, etc makes a lot of sense.

But I offered $200 cash for keys and they are voluntarily gone leaving the property in a clean condition today.