If that is what a person wants to do, then good luck to them, Personally I think it shows a lack of confidence, when you have to hide your face or neck at a Poker table, and if you want to hide your emotions you should stick to on-line games.
We had a player who turned up at our weekly League game who thought he was clever and cool wearing Sunglasses, but was ridiculed so much he didn't come back again for about a month.
I could understand a professional doing it if the game was being Televised and the studio lights were blinding him from seeing the flop etc. But even then there are very few others that do it, and they seem to manage.
When the fun Stops, STOP!