Here's something I didn't know.
From (US) Federal Trade Commission site:
"Also, if the loss involves your credit card number, but not the card itself, you have no liability for unauthorized use."
I have 4 members of my family using my main card so statements are huge. But I scan it every month for unauthorized sellers which are easy to spot. We have many transactions but we usually shop the same 30 or so places. A bogus 3+ figure payment would never be missed.
More U.S. info on CC, ATMs, and debit card safety: