Thanks David for your reply!
and yes most of the houses here including ours is light interior, plus shiny (works well to soft & reflect light)
some houses use beige. so basically i can get in a room that have all 4 walls bright white floor is made of beige marble, ceiling is normal tiles which they don't bounce good.
i did before some tests in my apartment which have dark porcelain (brown) colored walls and the results were not interesting most of the pictures looks dim or somewhat dark background, but in my parents house its a different story the flash bounce very good, i guess i will give it a shot and do more tests to see the results this week!
something else came into my mind just now...what about continues light source? like fluorescent light, or even strong LED light, i can get a strong one here too bright that it can reach over 2 kilo meters (i think im trying to blind people by hitting them with too strong lights