All BST's Owner should be actively maintaining their thread. If the thread is not closed, then effectively the BST is active.
If you find any BST that are not active you should be using the report button to alert a marketplace mod.
Any BST that is not maintained is a violation of Marketplace ToS of Section 4 of the Rules posted by
@Zwielicht which can be found -
https://www.blackhatworld.com/seo/the-black-hat-world-marketplace-rules.1295700/post-13962694
As for Joint Ventures, everyone should be doing their due diligence and research there.
I do however agree that all JV thread openers should be reporting their JV to be asked to closed if it is no longer needed or give updates if they are still looking.
perhaps
@Zwielicht, the same rules for maintaining a BST should be applied for all WTB/JV/HAF sections aswell? (Unless they already do)