Minecraft wiki entry for Multiplayer_PvP_bases, associated text: For extremely experienced hackers
The tricks above will not fool the most experienced hackers, who had personal experience with these kinds of things. For example, an experienced fly hacker might also turn on their LiquidInteraction to allow them to place blocks on any lava above and around your base, an experienced X-ray hacker may turn off rendering for ores while they find bases, or turn on rendering for dispensers, droppers, hoppers and minecarts with chests/hoppers. and an experienced teleport-hacker might be able to use X-ray to identify any defenses around it first, and remove them. However, a way someone can ultimately protect against any players is to make a completely un-raidable base, like above. While tricky, tough to gain resources, and sometimes fails, if you know how to make a nearly un-raidable base, you can survive nearly everything, but no base is unable to be raided.