After several incidents I have doubled up with redundant backups of all hard wired smoke/CO detectors.Several years ago I added (my daughters home) an FM system as a backup to the hard wired units because of the size & layout of the home.

1) I am never ok with a tenant violating a lease. 2) You have the right to know what is going on at your property and who is in it at all times.My advice is is the following:1) They need to be notified immediately if the breach and that you can terminate the lease agreement immediately.2) If you decide to profit share, I would suggest a new lease at a higher rate that includes a subletting clause holding you harmless if any and all liability or claims resulting from an incident at the property.

More the concern for improper shower curtain use due to the uncontained nature of the tub as we already had an incident of floor flooding through to the first floor from this.

We may not go to every crime that happens but the areas with the most incidents of fire and ems calls are not the places you want to buy.  

I also don't want to be left holding the bag, at the end of the day, if there is an issue or incident.

Also I had a similar incident with the threats and paying for someone to live/trash one of my houses for Free.

We had some incidents where tenants had done the damages while moving in and putting it on the sheet, it make it look like it was there before.

Maybe they did or maybe they didn't, but I personally would not want the courts to deciding what I knew at the time of an incident. 

The tenants that were released were the other roommates within the unit where the incident occurred.

You can also choose to only accept Airbnb guests who have been reviewed by other hosts to try and minimize any negative incidents or encounters with your guests.Start with doing a little research on Airbnb in your area for studio apartments or people renting by the bedroom.