Hmm... well here's my guess. Could be totally wrong.
Newegg gets three kinds of returns:
1. Someone buys something, doesn't like it, they send it back. Newegg tests it, finds it's good. Newegg can't sell it as new so they repackage it (frequently in the retail box) and sell it as refurb since they can't sell it as new. Generally how far off the retail price is from the refurb price tells you how much stuff comes with it... if a refurb is close to the retail price, it usually comes with everything. If the refurb price is much less than the retail price, it's generally just the card or board.
2. Someone buys something, and it's broken/breaks (but not cosmetically.) They send it back to newegg, newegg sends it back to the manufacturer to get 'replaced'. Newegg gets a whitebox product back and sells it as a refurb.
3. Third would be when Newegg gets a cosmetically broken product. Chips, scratches.. whether or not it was damaged by a customer or possibly just in the shuffle at the actual 'store'.. generally you can't return a cosmetically damaged product to the manufacturer to get replaced. So Newegg just accumulates a stockpile of these cosmetically damaged components. CPU's with chips, motherboards with resistors broken off or battery clips broken, DVD drives without bezels. After newegg accumulates a bunch of these, they place em in the refurb section as good/bad. It's pointless for them to test them, because functioning or not, they can't sell them as refurbs or return em to the manufacturer.. so they just sell em in bulk, under the generic tag saying they might or might not work. I believe that's why all of those bulk descriptions have the 'scratches and chips' clause in them.
If I were correct, then things like DVD drives (where cosmetic damage doesn't mean a damn on functionality) would be a better buy then say CPU's where a chip on the core can mean it's worthless.
Of course, this is all speculation, and anyone else's guess is probably better than mine!