QuickBooks is the most recognized software for small businesses. It is also fairly easy to use but can be easily messed up by an in-experienced person fairly quickly. Just because someone has an accounting degree, or worked on QuickBooks five years ago, does not mean they know the program well enough to help you as the business owner.
It is actually fairly easy to see if a bookkeeper knows the program. What I usually do is customize a report in QuickBooks by changing the fonts and the location of a few columns. I normally use a fairly common report such as the customer list or a balance sheet comparison. Then I give the report to the new bookkeeper to see how long it takes them to re-create my report. I know how long it took me to create. If they can do it in no more than 15 minutes longer than it took me, then they are fairly good, if they can do it faster than I did, then they really do know the program well and should be hired immediately.
Keep in mind that knowing how to customize a report does not mean they know the accounting behind it. However, if you have two people you are selecting from for a bookkeeping job, this is a good way to determine which is better for your company. Customizing templates in QuickBooks is a feature that is normally not done and rarely taught, so if they know how to do this then they have spent enough time with the program to more than likely be helpful to the small business owner.