11. You can't attract new IT staff
The candidate's enthusiasm rapidly fades and they terminate the interview having realized you are not particularly interested in the last 5~10 experience on their resume nor their latest product certifications.
[Aside: A few years back I had exactly this problem with a datacentre transformation and virtualisation project, where we uncovered 100+ NT servers and needed to assemble a team to "unravel the spaghetti".]