None of us can escape a bad hire.
It's a scenario that plays out too often in tech companies, big and small. And it costs up to 30% of the employee's first-year earnings. That’s not a number to be ignored.
After working with thousands of developers, we identified 5 signals that give away a bad hire. Consider these as eliminators, rather than selectors.
Always use this list to think twice before extending any job offer:
#1 - The expert in everything.
True experts have depth, not just breadth.
So, be wary of candidates who claim expertise in an unrealistic number of technologies. Unless you're interviewing for a very senior position, anyone promising mastery in 10+ tech stacks is likely overstating abilities.
Look for candidates who can discuss their primary skills in detail. More importantly, look for the ones who admit what they don't know. A developer who's honest about their knowledge gaps is more likely to be a continuous learner.
Encourage this with questions like, “On a scale of 1-10, how would you rate your proficiency in JavaScript? Can you explain why you gave yourself that rating?”
This gives you a clear insight into two things: their actual expertise and their self-awareness.
#2 - The incurious one.
Engaged candidates ask thoughtful questions about the product, tech stack, and company culture. They want to know the challenges they'll face and the impact they can make.
If a potential hire sits through an interview without showing curiosity, it's a red flag. Genuine interest is key for long-term fit.
Look for candidates who've done their homework – they should have basic knowledge about the company and be eager to learn more. Encourage questions throughout the interview and pay attention to their depth. Are they surface-level inquiries anyone could ask, or do they demonstrate real thought and interest?
Some may not be proactive, but will still have questions. Always ask a specific question about your product/company. For instance, “What are the 2 things that can be better about our product?”
#3 - The past job complainer.
How a candidate speaks about their past experiences can be very telling.
While it's normal to have had some negative experiences, a pattern of complaints about former employers, colleagues, or projects is a warning sign. Professional candidates focus on lessons learned and growth opportunities, not personal grievances.
During the interview, ask about challenges they've faced in previous roles and how they overcame them. Pay attention to their framing – do they take any responsibility, or is it always someone else's fault?
In case they don’t know when to stop, always ask them to pause first. Give them a chance. Nudge them with a, “Can you reshare this experience from the point of view of what you have learned?”
If they still continue with a blaming attitude, dodge the bullet. After all, today's critic is tomorrow's complainer.
#4 - The vague responder.
A strong candidate should be able to clearly articulate their role in a project, the technologies they used, and the outcomes they achieved. And the rationale behind all of it. It reflects their true involvement and understanding.
So, be cautious of candidates who can only provide surface-level descriptions of their work. Unless they go into details themselves, prompt them with questions like, “Tell me 2 strong reasons backing your choice of tech stack” or “If you were to do that project again, what would you do differently?”
If responses don’t really explain the “what” and the “why” of their work, make a note. It might indicate limited hands-on experience or a tendency to exaggerate involvement.
#5 - The non-learner.
A candidate without a learning attitude is a liability in the long run. Continuous learning isn't just nice to have, it's essential for keeping up with rapid tech changes.
So, look for someone who shows a learning mindset.
During the interview, inquire about their recent learning experiences or new technologies they're excited about. You want signals for self-driven learning. It could be their recent reads, side projects, freelance experiences, courses, or contributions to open-source projects.
In tech, we don’t just hire the skills of today, but for the ability to adapt to what we’ll need tomorrow.
Do not compromise on learning as one of their strong soft skills.
Your hiring safety net
Hiring is never a guarantee, but these red flags can be your early warning system against potentially disastrous hires. They are hard-won lessons from countless interviews and hires.
Remember, you're not looking for perfection. You're searching for a developer whose strengths align with your needs and whose weaknesses don't contradict your goals.
So, use this list not to filter out bad hires, not select good ones. They all will pass this checklist anyway.