1) Rifles are more valuable than smoothbores to collectors. So there is some bias to calling it a rifle if it looks like a rifle.
2) A good many rifles got converted to smoothbore, at least in the East. Less so in the South and in the West. So it’s common to surmise, hope, or state that “it was most likely rifled, but got converted to smoothbore during its working life. Often true but hard to prove. See #1 above. There’s increased coolness and value in rifles.
2a) factors arguing against a gun that is smoothbore now, having been rifled when built (influences, not definitive): round or octagon to round barrels, no rear sight, fowler style guard and buttplate. But note that there are zero classical Bucks County “rifles” currently having rifled barrels, to my knowledge. That suggests that though rifle-built, they were always smooth rifles.
2b) factors arguing for a rifle that is smoothbore now, originally having been rifled (influencers not definitive proof): double set triggers, very small caliber in a heavy barrel, Southern Mountain origins.