Any decent engine builder will be happy to take a look at it for you i'm sure.

They will be able to tell instantly if its damaged or badly worn.


When a cam is new the lobes are a kinda black freckle effect, as they wear the freckle wears off and becomes a smooth silver most of the way round the lobe, generally the flat part of the lobe will always retain some freckle, and the point of the lobe will wear quickest.
If the freckle has gone all the way round, i'd replace it as a matter of course.
If there is any scoring on the lobes or bearings i'd also replace it.

Hope thats some help.