does manners really matter?

Do people actually notice if you tilt your soap bowl away from you? Or whether or not you know how to leave your plate after you're done (fork and knife and/or spoon horizontally placed across the plate or bowl)?  Or how about having both hands on the table and your left hand holding the plate or whatever?  Have you ever found yourself noticing, oh, that kid has both hands on the table, what a polite and well cultured child that must be.  Hmm? 

Sure it looks nice to actually look like you're eating, and being quiet, and acting nice, but do people actually notice?