I hear that. I offered MSN/ICQ/AIM support for awhile, and was always getting kids trying to pose as customers they knew I hosted and get logins and passwords. One night someone almost had me fooled, but then had no idea how the account was paid. That's pretty much my requirement; I either email the info to the owner's email on file, or they have to identify the last 4 digits of the credit card number used on the account, or something similar if they use paypal, etc.
In fact, that's how I got the guy, I asked for the credit card information, and he went into this "I used my dad's and don't have it right now." when the account was actually paid via PayPal.
*sigh* I finally had to quit offering online support because of customers, though, who would either (a) start using me as their tech support guy and try to ask questions for hours about absolutely anything computer-related, or (b) when I would be offline, customers would sit and wait with an urgent request instead of emailing me, and then be upset for my slow response time when I was available on email the whole day. Plus it was so hard to keep track of legitimate requests without the trail email provides. Basically, what was supposed to be a convenience for the customers turned into a major negative. I ended up using a nice ticketsystem that fixed everything.