I think we to distinguish two things at that point:
1. WHEN did actually became a "fan"(whatver that may be

)?
2. By WHICH SONG did you became a fan?
I agree with Mike that people who became a fan after CRUSH or Bounce are the new fans because you can say as much as you want but BJ IS a different band these days then they were till '96.
And yes I say: old fan=rock fan; new fan=pop fan
I mean you can read customer critics of BOUNCE at amazon where people say that the best track on Bounce is Open all night
About the second thing:
I became a fan in the these days era but didn't make it public because it was really painful to be a BJ fan at this time(not as much as today but still

). But I became a fan when I heard "Runaway" on the radio and wachting "prayer" on the TV; and then when TD came out I saw TD and TAALS on the TV so I went out to buy Crossroad. So I consider myself as an old fan.