We can all relate plenty of stories about visiting a business to enquire about buying a specific product, only to leave dissatisfied with no answers to our questions. This is often the result of poorly trained or poorly informed staff.
Being able to pass on knowledge about the products that you sell is a big part of customer service. Your customers are coming to your business because they want answers to their questions. If they can't get answers from you, they'll go to another business that can provide answers.
This is a common problem in business today, with business owners being encouraged to employ younger staff so as to keep costs down. Their hourly rate may be lower, but so is their level of knowledge and their sales skills in general. If you want your business to succeed, give your staff every opportunity to learn about the products they are selling. Don't blame your staff for not knowing the answers to customers' questions if you haven't taken the time to teach them what they need to know.
Some businesses seem to be able to answer just about any question that you can possibly think of. Others struggle to answer the simplest of enquiries. Those that have the better ability to answer questions are offering higher levels of service, and I believe that in the long run they will be far more successful.