[U-Boot] NAND flash - bad blocks

[Dimitar Penev <dpn@switchfin.org>]

Hello,

First of all sorry if this question was already answered here.

We are sourcing some K9F8G08U0M-PIB0 NAND flash devices.
On the first erase in uboot 2011.09 I got bunch of mostly consecutive bad 
blocks.
According to the datasheet we should get not more then 80 bad blocks for our 
chip
but I get something like 240 bad blocks for most of the NAND chips.

I seems to be able to fix this using the following procedure:

In uboot
uboot>nand scrub.chip

In uboot
uboot>nand erase.chip clean
at this point I get usually 1,2 bad blocks which looks normal to me.

In Linux we have few mtd partitions on this NAND chip.
Unmount all of them and for all of them :
linux>nandtest -m /dev/mtdx
Usually this doesn't add any new badblocks on top of what I get on nand 
erase in uboot,
but I really haven't tested that much device to say.

After this procedure the NAND flash seems to work fine.
Do you think this is reliable way?
Is there something better I can do?

Has anyone got NAND component batch having more bad blocks then datasheet 
allows.
Should we consider the provider unreliable?

Thank you
Dimitar