I know what you mean Tamirra, I would feel loathed to eat from someone a bit grotty looking.
But as others have said, horrible teeth and bitten nails, don't indicate an unclean person, maybe the bad teeth are as a result of some childhood illness and genetics and maybe he feels so nervous when he visits your home, for fear of your disapproval, he's bitten his nails to the quick.
Surely if you've raised your daughter in a clean and decent manner, she wouldn't want to date someone who was unwashed and had filthy habits. You should probably go for the meal and just eat the food, don't think about how it was prepared, just grin and bear it, to keep the relationship between you and your daughter on good terms.