When hiring anyone for any reasons, references are a must. Those that work with children, the elderly, or in any patient care environment must have some really good references on top of a spotless criminal record. If you are hiring someone, you should never skip over the references when considering a person for employment. The problem with this, however, is that there are some things people can not answer, and even some things you should not bother asking. Laws differ, so find out what applies in your particular case. You can then decide with reference check questions you want to ask.
The first reference check questions that anyone should ask would be to verify employment, as well as start and end dates. In some areas, this is all that someone can ask. As strange as it sounds, some can not ask if someone was fired, always late, or if they did a good job. The reference can state those things, but they can not be asked. In most places, however, these things can be asked, but you should always do so in a delicate manner. Reference check questions should pertain to what you need within your company. If being late once in a while might not be an issue, you may not care as much about that. No one wants someone who is always late, however.
You should always include questions for references about how well someone preformed their duties, and what those duties entailed. Not only do you want to see how they did, you also want to be sure they are not fudging on their resume. Someone that does that is never a good candidate for hiring. You can ask about how they got along with coworkers and how they were about communications and meeting deadlines.
Other reference check questions you may want to ask will be tailored towards what you need in an employee. Organizational skills are always good for almost any job, and so is a positive attitude. Someone that goes above and beyond what they are required always makes a good employee, so think about adding those things to your questions for a reference check. If you have a hard time thinking what to ask, look around online for examples or books on the subject. Those that are going to be doing a lot of hiring may want to look in to some books about HR so they have reference right there at all times.