The prostitute cannot be tracked down, thanks to the anonymity of the internet. You don't have a name, you don't know where they live, they are just gone. Anything can be ho-snagged, although small valuables that wont be missed until later are the most common: cellphones, netbooks, etc. However, if the john is into bondage, this allows the ho-snagger to take bigger ticket items: TVs, stereos, computers couches, etc.
The theft could occur afterwards as well, as the prostitute may just case the place during the initial business transaction.