It's not an addiction, its a phase. When an engineer is young, they will do anything to make something work. When an engineer is older they've learned how to

It's not an addiction, its a phase. When an engineer is young, they will do anything to make something work. When an engineer is older they've learned how to make things work, but then learn that changing things in the future can be hard. So they try to build as many hinges in as many places as possible. Many years later they will realize that only 1/10 of their "flexible" solutions needed to be as flexible as they made it, and then they become experienced developers who know how to build something that works, how to build something that can be flexible for the future, and most importantly they learn how to question if the piece they are making needs to be flexible (or even better question the business if it needs to be built at all). I'd say the test shouldn't be, how can you find out if they are in the overengineering stage or not. Instead, I'd filter for engineers who can be reasoned with. If you are an engineer in stage 3, it's okay to have a stage 2 engineer on your team, but if he can't take direction then he'll be a liability.