This comes down to who you are giving you card details to, with it certainly true that there are good and bad online casinos. If you are depositing to a casino based in the UK you can almost guarantee that it will be safe. However if you are making a deposit to a Curacao casino or another less reputable gambling jurisdiction, it's important to get a guage on the reputation of the site before making a call. Other telltale signs a casino is a no go, is a lack of SSL on the website or no or non-respondent customer service department.