If the fish has ich you will see them but most other parasites won't be noticed visually.A good deal of dats and other wild caught fish have parasites when they are brought in.
I found that my Indonesian Tigers used to do that a lot especially when they were fed market prawn. Right after a feed of prawn they'd constantly rub the driftwood for a few hours. None of my Thinbars, Silvers or NGT ever did it