Hard disk warranties: worthless?

1984 writes: Earlier this year I returned a Hitachi 2.5" drive under warranty, and got back a replacement which died after a week or so's light use. More recently a Seagate 200GB desktop IDE disk flaked after a few months use, so I sent it off and received a replacement under warranty. The replacement wouldn't even format. So I RMAed that and got another dead replacement. All the replacement disks were "refurbished", and I see many instances of similar problems with refurb. replacements when Googling. So I'm asking, what experience are people having with getting replacement disks that work, and continue to do so for something approaching the expected lifetime of the original drive? Are current warranties just a sham?