Subscribing to threads

Just a quick question, must have a knack of subscribing to threads that get deleted, whether it is a hoax or whatever, but why is there not an explantion of why they are gone. As an example, I subscribed to about 5 threads on night, and 4 were gone the next day, and could not find the threads. No 404'd or anything. No need to answer on here, please U2U me, as I'm sure there is more to deleting threads than thought.

Thank You in advance.