If you have a applicant in front of you who seems like a appropriate choice, you definitely want that person to agree to your job offer.
From time to time, though, you know the job has natural challenges or downsides, and you may be afraid if you speak about these thing you will lose a decent employee.
The problem is, if you hire them and they find out the negatives themselves, you may well lose them during the first week.
That is why be candid about challenges in the job or inside the company.
Look for candidates who embrace and relish the challenges, and who are able to see beyond the negatives. These can become your most appreciated employees.