If you are on a specific mission, as catching that first steelhead on a fly, tell him so. Not if you feel you are still learning how to catch them on a fly. Flyfishing steelhead is tuff. You have to want to. My gear guide friends do the same for me, for the guy who simply wants to flyfish.
Guides specialize by doing what they do over and over, day in and day out.
You simply can't get good at a style of fishing that you don't do. Only in the eyes of the angler booking the trip. Ask the right questions and tell them what you want.