I let a guy use my iPhone 5 while we were in Vegas eating in & out burger in the parking lot. The guy was a construction worker who left his key in the truck, accidentally.
I dialed the number, let the guy use it, while waiting next to him. He called and asked help for his emergencies.
Not that I like doing it, but in emergencies, I'd help out while trying to minimize the fall out.
Once I got the phone back, wiped them out with baby wipes, thrice, and clean the glass up with eye glasses cleaner cloth.