Bonjour John,

When 'sentir' is used to mean 'to smell like / of [sth]', it always uses the definite articles as it is referring to something general. 

See example below (always with the definite article):

Ça sent le chocolat = it smells of chocolate

Ça sent le brûlé ici = it smells of burning in here

Ça sent les chaussettes dans ta chambre = it smells like dirty socks in your room

I hope this is helpful.

Bonne journée !