Finger Licking Edit Meaning

1.

This is a gross habit that people initiate when they are eating. The louder they suck their fingers when they eat, the more horrible and worse it is. There are things to prevent this: see napkin, manners.

If people think childishly sucking on their thumbs or biting their fingernails are nasty and bad habits, then why don't they think the same bout finger licking? What do they all have in common? They all involve fingers in the mouth!!!