I suspect a hacker more than I suspect a corrupt dealer. I never gave out my credit card number to any unreputable company online. In fact, I think it was a purchase I made on amazon.com that gave my number away.
In reality your credit card number is much more likely to be taken an abused during a real world transaction. Every time you use that card you are handing out the number to the person behind the counter and to every person that works there, and in many cases every person who will ever work there.
Often times those clerks can even look up old transactions. At my place I can look up the credit card number of anyone who EVER did business here. Basically anyone who wants to can get access to thousands of credit card numbers. Why people try to hack them off computers is a mystery to me, when they could just go get a job at motel 6 for a week and copy a backup disc and take home 1000 numbers all at once.
It all basically boils down to this. Any business is susceptible because the front line "just over minimum wage" employees have access to the numbers. That means that YOU are susceptible if you ever use a credit card anywhere.
Retail establishments usually are not that bad because the clerks are already being watched carefully for theft, and they often can't look up old transactions.
But anyplace that can take numbers over the phone. and anyplace that only runs a couple of employees at once are bad for this. Hotels are probably the worst. They are often lightly staffed in the evenings (often just one person). They usually have huge guest reservation database systems which allow the worker to look up pretty much anyones number who has ever stayed there, including cancelled reservations.
Gas stations are bad because they usually just have one person working, who can print up duplicate receipts and pocket them all day long.
Restaurants are bad because the servers can go back and stick in whatever tip they want (assuming you didn't write anything on the tip line, and even then they can often still do it). Then when the bill comes most people have long forgotten the exact total, and even if you don't forget, and you pursue it, it only gets blaimed on a typo (assuming the server still works there at all).
Those are all just a few of the reasons I don't use credit cards and I don't have a bank account.