I don't remember exactly the scenes as the game has over 100 but I remember in some cases it changed the dialogue at least. Even having pubes or not or being tanned or not changed the dialogues in some cases.
I assume lust will be used for the lowest morality things like having sex with the hobos, you won't be able to just have low morality you'll need high lust as well. That's my guess.
Is this some kind of mod or will it be possible to customize the character further along the plot?