I'm curious about your criteria to judge a rubbish thread or not.
Can you give examples (links) and a bit of explanation why you think they are rubbish?
Anyway, if you know some rubbish threads, you can use "report to moderator" feature. Have you done it?  

WOW, it seems you have an ideal crypto/Bitcoin forum. Can you tell us what forum it is? AFAIK, bitcointalk is still the best forum I've ever known. CMIIW

Check this: https://coindiligent.com/5-best-cryptocurrency-forums-to-start-using-today