Reproductions: How do you know they're accurate?

Since there seems to be so much more interest on this vintage site in reproductions rather than original garments, I have a question. How do you know that what you've bought is an accurate reproduction? Have you handled an original to have a point of direct comparison? Have you done research into styles, how they were originally worn, what they were made from and how the designs changed? Do you simply buy into the marketing?

My wardrobe has shifted more and more toward reproductions in...

Reproductions: How do you know they're accurate?