@Pippinwhite: Tell me about it! If I ask a consultant, whether an individual salesperson or someone at the cosmetics counter, about a product, I expect them to know something about it (if they're an individual consultant) or know whom I can speak with if I'm at a cosmetic counter.
But yeah, you have to be very, very tactful with some customers who want exactly the wrong color for their skin (or age). I've watched in awe as a good consultant managed to steer customers toward something much better for their skin without causing offense. It's a gift.