I am not a fan of hearing from a hiring manager, department head, or recruiter that an interviewee "bombed" an interview, only for them to respond to my inquiry of how said interviewee "bombed" their interview with a series of statements and question responses that paint a clear picture of rampant personal and organizational implicit bias and irrelevant interview questions at play. You'd "bomb" an interview too if you were set up for failure as soon as you walked through the door by the company itself!
If you're conducting an interview to fill a position in your department/organization you need to be cognizant of a few things to ensure you are giving the candidate an opportunity to sell themselves to you — and giving yourself an opportunity to sell the position and the organization to them.
Understand the personal and organizational biases at play in not only your department but your organization as a whole. Write them down. Refer to them regularly throughout the entire hiring and recruitment process.
Create a list of the 5-10 top attributes you are looking for in someone who would excel in the position you're trying to fill and compare this to your list of biases to ensure none of your biases are at play and/or none of your top attributes are selfish in nature.
Utilize and create interview questions that actually align with the position you're trying to fill, preferably behavioral and focused on the top 5 - 10 attributes, to ensure that you are able to acquire clear insight into what the candidate brings to your job opening and how they might excel and thrive in your company.
Arguably the most important thing to acknowledge is simply understanding your department and your company enough to know what kind of environment you are possibly going to bring someone into. If you have a departmental and/or organizational culture that would hinder a great candidate's ability to thrive at your company, whether it be due to negative cultural norms, a lack of inclusivity, or very particular biases that are expounded department or company-wide, then you need to begin looking at how you can address these issues within your department or organization to create a more inclusive environment. No matter how hard you work on bettering interviewing acumen and recruiting practices bringing people into an environment that stifles them is doing them and you a disservice.
While all of the aforementioned are essential and go a long way toward improving your interviews please understand that they are only the tip of the iceberg, so to speak. There could be many other factors that could come into play: unclear or unwelcoming job postings; the reputation of your company in your community that you serve; your professional reputation in the community; and the competitiveness of your organization just to name a few. With that all said, next time you feel like someone "bombed" an interview ask yourself was it completely on the shoulders of the candidate or did you have a part in their recruiting demise?