…..again, in one piece famous people are not really recognized by their appearances, they are recognized because of rumours around them and their legends.
---- people only recognize zoro because of his 3 swords.
---- law only got recognized because of his whitebeard tattoo on his back.
---- luffy because of his strawhat
---- law because of the 100 hearts he sent to the WG.
---- rayleigh only got recognized by guys who really idolized roger and marine officers.
unless these people go around announcing themselves around, they can roam around as long as they conceal themselves as littlest as possible.
even royalties, (vivi) who are supposed to be more popular are not recognized too often by people.
and even if you can make a counter-argument for it, admirals dont really dont go around in public too much. plus fujitora is a new admiral.
and him not recognizing luffy because he is blind could be valid in real world, but this is one piece, where disabled guys are much stronger and are much capable. maybe its CoO or adept senses. but i bet he knew he was being cheated at the casino, so if he can sense the simple casino balls, he will damn surely sense people around him and their presence/intent.