I once accidentally deleted a large part of a production private nntp spool (used as a tech support forum for a commercial product) while trying to get replication working to a backup. The same day, I did a recursive chown on a different production server from /. Worse yet, I was so distraught that I left the office without telling anyone in a position to fix it. Since then (over 20 years ago now) I always double check where and who I am before doing something destructive and dry run if possible, but more importantly, clearly and quickly communicate when I screw up.
I ask junior folks what their biggest (technical) screw up has been, in interviews. I think it's a bad sign if they won't admit to it or claim they've never screwed up big-time.
Hopefully you ask this to senior folks also. Folks without much experience or responsibility may have not screwed up too badly yet, but I agree it would be a bad sign for anyone with significant experience to have never broken something.
I ask junior folks what their biggest (technical) screw up has been, in interviews. I think it's a bad sign if they won't admit to it or claim they've never screwed up big-time.