According to research published in 2015, with 10 likes, a computer model knows you better than a colleague; with 70 likes, a model knows you better than a friend or roommate; with 150 likes, a model knows you better than a family member; and with 300 likes, a model knows you better than your spouse. In addition, with similar data, models can predict private traits like sexual orientation, religous preference, and politial views.
Given that these digital breadcrumbs can be used to discriminate against us, it seems like there is a place for a service that will randomly like things to throw the Facebook algorithms off our digital scent. As a result, your profile will show you "liking" things that don't reflect your taste.
And, to mask purchasing behavior, consider having a group of people use a shared Amazon account.