More information about the security implications of Facebook’s “Like” button have surfaced. It now appears that you don’t even have to log in to Facebook or click the button in order for it to track your browsing habits.
Even if someone is not a Facebook user or is not logged in, Facebook’s social plugins collect the address of the Web page being visited and the Internet address of the visitor as soon as the page is loaded–clicking on the Like button is not required. If enough sites participate, that permits Facebook to assemble a vast amount of data about Internet users’ browsing habits.
“If you put a Like button on your site, you’re potentially selling out your users’ privacy even if they never press that button,” says Nicole Ozer, an attorney with the ACLU of Northern California. “It’s another example of why user control needs to be the default in Facebook.” Source
I hate sites that have Like buttons or present me with pop-ups asking me to login with my Facebook account. That is why I try to avoid those sites at all costs. My data and click path across the web should not be recorded by Facebook.