Old conspiracy theories about Fort Knox's gold are getting fresh attention, which matters for anyone watching trust in the dollar and gold prices.

• Some people believe the US secretly moved or lent out most of Fort Knox's gold decades ago, leaving an empty vault guarded for show.
• No outside visits or independent audits are allowed, which keeps the doubts alive.
• Officially, foreign-owned gold stored there was returned to its home countries long ago, and what remains is supposed to be US-owned.
• During the 2008 financial crisis, some suspected the US quietly sold or leased gold to hold down prices or raise cash.

Outlook: Without an independent audit, the lack of transparency will keep fueling distrust and gold-related speculation.