+1 - you can mark the bevel with a black Edding to see it better. Just one slight stroke on a finisher is enough to see if the razor was honed with or without tape.
The angel of a bevel is esential! - not necessarily for the sharpness or smoothness though, but like on every knife it determines the lifetime of the edge together with steel quality and tempering. This is of less importance for us nowadays since we have time and (most of us) can hone their razors. But it was a very important property in the older days for the barbers. Beside this, thickness and strongness of your beard hear has an influence of the perfect bevel-angel for you personally.