I only tap mine if there's a reed sticking.The main drawbacks to harmonica playing are facial hair (ow! that hurts!) and the small bits of detritus that get stuck in the reed and then release quickly on a suck note, hitting the back of your throat with extreme velocity.
While the gob iron players are here, might I extoll the virtues of the 'low F' harmonica. F is a good singing key and the normal F is a bit squeaky. Get a low F, they're wonderful, especailly those clever valved ones. And you don't get your hair stuck in them either.
Keep on sucking
Les