@Alicia828 It’s understandable, your hesitation to leave an honest review, given what you’ve shared. Your fellow hosts do appreciate your desire to do so anyway. "Is there a way to warn other hosts without the guest being aware?" I'm afraid not. This is how reviews work on Airbnb,
https://www.airbnb.ca/help/article/13/reviews-for-stays
The thing is, if missing towels and a couch tear were the worst of the guest’s transgressions, I’m not sure a ‘terrible’ review is warranted (though it would have been nice for the guest to inform you of the damaged couch). Once you’ve had a guest throw a huge party, trash your home and/or steal the tv, smaller incidents like missing tea towels are often put into perspective.
Was this guest new to Airbnb and perhaps a bit uninitiated in the etiquette of being a guest? Is it possible the guest used the towels for cleaning up some messes and they were ruined in the process and they threw them out?
You can always start a review for a guest you found difficult by saying something positive, and then mention the issue. Perhaps for this guest you could say their communication could be improved. You have the option to include private feedback to the guest when submitting the review. You might just mention that it’s good form to let a host know when things get damaged or go missing, ask them what happened with the towels, and say that you would have appreciated a note about the couch.
With Airbnb, prevention is the name of the game. Going forward, watch for certain red flags and don't hesitate to decline a guest you feel uncomfortable with. Local bookings can often lead to problems. Search this forum to learn about other possible red flags and various hosting pitfalls.