If you like a page, Facebook uses it in your friend's feed sometimes to show other people that you like that product, service, or items. If you decide that you "unlike" something by removing the like, how long can they continue to advertise your like? Just because you clicked something once, do they have a right to forever more use it? How often are they required check whether it's been unliked? Do they do it in real time? How long until the cache or "eventually consistent" data becomes consistent?

Only 40% of Facebook users have ever unliked anything.

Timeline makes it so that users of the Open Graph know if you've EVER liked something.

Facebook Platform policy is wonderfully not specific: "You may cache data you receive through use of the Facebook API in order to improve your application’s user experience, but you should try to keep the data up to date."

Wasn't it Yoda who said that there is no try, there is only do?

I had to like a page, just to post a customer complaint that couldn't be handled through their traditional customer service so that it would get the proper attention, and then I unliked it. Making you like a page just to register a complaint kind of adds insult to injury.

It also does seem to go against the spirit of what LIKE means.