I can't agree enough, I've always asked to see my work area at every interview I've been on. I've been willing to accept some abysmal conditions in the past depending on other factors. Nobody has ever refused to show me but if they did it would be a huge red flag unless there was some obvious security limitations/rules preventing it.

While you are correct that most DBAs will spend a large majority of their time optimize existing queries, fixing existing databases, and just overall improvement of existing setups. This is the norm of a DBA, if you find a job where all you do is basid admin of the server, then you're a server admin, not a DBA, and I wouldn't consider you worthy of a DBA job role.

This is like a programmer walking into a job and complaining when he has to rewrite/improve/expand existing code. Writing stuff 100% from scratch is not the norm, having to work in or with other people's code is.