You should always wear your boots with socks. It would look strange and feel uncomfortable to wear boots without socks. If you want a sheer look, you could wear pantyhose instead, but they will probably be ruined after one use.
It's always a good idea to wear socks with boots so your boots don't rub on your feet and cause your feet to blister. If they are short boots you can find ankle socks at the store.
always, if you dont wear socks your feet will sweat and then your boots will smell. Your socks do not have to be visable and in most instances will look better if they were not. Usually the top of the boot would be cover anyways and its just better for your feet and the boot the use socks.