Entity-Attribute-Value (EAV) database model
Premature optimization - the root of all evil. Or something like: we think that in the future we will need this and that feature, though in reality, in most cases, we do not.
Sometimes when you come to the project, you see EAV database design, and some developers hate it, some do not have an opinion, and the rest do not care. Majority of database designers and developers would tell you that you should use a typical relational model, with all its tooling available out of the box, instead of handcrafting everything on your own. I agree on that, but is there a case when EAV is good?