Hair straight = dirty

Moriah
Hey stylist! I have naturally curly/beach style hair. 
It's like if I don't do anything to it it's like that but if I comb it out when it's wet I can make it straight. 
Anyway when my hair is straight sometimes just a day old makes it look oily/dirty. My hair is oily anyways but not the day after if it's in its natural state 
I do use a dry shampoo in between washes, and try to wash my hair twice a week in case you wondered.