If you purchased the item under your current membership (many people have multiple memberships) (or know which one you used- or have the original legible receipt) it makes the process much easier. Basically as long as you are not abusing the system (I've seen some refusals with 10+ year old TV's purchased prior to the integration of the 90 day return policy) that people have got their full use out of, but still want to upgrade to a 55+ inch LCD when the screen dims...

Food returns seem to be usually rotted food or poor taste...

Luggage... it seems to be as long as its not self inflicted (blatant abuse) they should be ok...

The longer a person has been a member should also have some clout (assuming they don't routinely return items as a 'rental' )