In the past, I've been asked to leave my passport as guarantee when hiring a car or motorcycle, even in some hotels - mostly in Thailand.
DON'T
I've always refused, concerned about it being stolen.
http://www.nationmultimedia.com/nationa … 28911.html
In Phuket, police are studying a statement from the owner of a motorcycle rental shop in relation to an Italian man whose passport that went missing in July last year. In Pattaya, police are also probing an online booking made with a local travel agency, with the tickets being bought with Thai baht.
Stolen and sold on by a dodgy shop, ending up being used to board an aircraft illegally.
As I suggest, when someone asks to keep your passport, tell them to sod off.