This is something I actually don't do. I don't see anything wrong with it, it's just not my approach. I want them to see what we do, and be able to decide if it's a fit for them. I'm hoping that if it's not a fit, they'll figure that out (or at least get some inkling) from that first class.
I don't think those are necessarily mutually exclusive. If you know your potential student's goals, you can show them what you do, and also explain to them how it relates to their goals. At least theoretically - this is something I'm still working on myself.