I know about NIJ standards because of my job, but is there any group or organization that independently tests things like sleeping bags to ensure they meet their advertised claims?
ASTM creates testing guidelines for things like sleeping pad R-values, sleeping bag temperature ratings, and garment waterproofing (measured as hydrostatic resistance). If a manufacturer says their numbers come from ASTM standards, you can generally trust them and compare with other brands using the same tests. Faking ASTM results would be considered fraud, not just exaggerating claims.
Gear Lab is probably the closest thing you’ll find to independent testing for outdoor gear.
ISO 23537 is the standard typically used for testing sleeping bags.
I don’t know why people are downvoting this question. It’d be awesome to see a group like this do independent testing.