It's actually not hard to get caught using a wireless signal... Anyone broadcasting a signal has access to all connections made to that router... All information has to go to and from that router in order to access the internet. This traffic can be seen with the proper tools and can also be read, in the case of WEP( WHICH IS AMAZINGINGLY INSECURE), or can be decrypted, such is the case with WPA and other strong encryption types. You're information is not necessarily safe... But this does of course depend on where you are connecting and who you are connecting too.