can a busty lady of bra cup size 38 C wear a padded bra ?

Yes.

I am a size 36DD or a 36E (depending on the bra) and yes, i am busty and yes, i do wear padded bra.

They are more firm and comfy in comparism with the non-padded bra.

besides, they look more sexy

i think you can but with the light padded bras. not the big padded ones. you are already "blessed", so no need to over pour

My friend that deals in d sales of lingerie says they are actually good for all kinds of bust. she corrected me when i called them padded. She says they are termed lined. Wearing them is supposed to give support to breasts and condition them to stay firm. Moreso, their being lined may prevent the "headlights" syndrome observed in the chest area( though the use of pasties or petals is always advocated).
Can't say though if they can help in reversal of the effects of gravity but one can try.