The Hire I Regret Looked Perfect on Paper

The hire I most regret looked perfect on paper. The hire I'd repeat in a heartbeat didn't. Twenty years of building teams keeps teaching me the same lesson: skill gets you in the room; character decides whether I'd build anything with you.
Here's the uncomfortable asymmetry. Skill is teachable. Character mostly isn't. I can train a capable person into a great one — I've done it dozens of times, coaching support and engineering teams to 85%+ client retention. What I cannot do is retrofit integrity, reliability, or basic decency into someone who arrived without them. You hire the résumé, but you live with the person.
The most expensive hiring mistakes I've made weren't people who lacked ability. They were talented people whose character quietly cost more than their output was worth — the brilliant one who cut corners, the impressive one who was generous with credit and stingy with blame, the star who treated juniors as furniture. Their work looked great in isolation. What it did to trust, morale, and everyone around them didn't show up on any performance review until the damage was done.
So here's what I actually screen for now, underneath the skills:
How they talk about their last team. Relentless blame of past employers is a preview, not an anomaly.
Whether they own mistakes without being cornered. “Here's what I got wrong and what I changed” is worth more than a flawless track record.
How they treat people who can't do anything for them. The way a candidate speaks to a receptionist or a junior tells me more than the interview does.
Reliability on small things. Someone who honours a tiny commitment — a callback, a deadline that didn't matter — will honour a big one.
None of this means hiring nice-but-incompetent people. Skill still has to clear the bar. But between two candidates who are both capable enough, character wins every single time — because ability compounds only inside someone you can trust, and no amount of talent offsets the cost of someone you can't.
Hire for the person you'll still respect after the honeymoon ends.
What's the trait you now screen for that your younger self would have overlooked?