Others like Bietran are now UNESCO protected castles, and are tourist attractions.
Others, like Bran Castle are famous by the people who lived-- or didn't live there. Queen Marie of Romania lived there, but not a Count Dracula. Count Dracula was made famous by Bram Stoker, as was this castle-- Bran Castle in Transylvania.
As for others, they are ruins in a national park, and are left to fall into disrepair. In this case, it is just as well since Elizabeth Bathory lived in these walls-- and she was a notorious serial killer.