People keep asking me what "Pristine" means, and I'm tired of having to re-re-retype everything every time, so I think I'll just gather everything about "Going Pristine" in this thread 
What does "Going Pristine" means
Going 'Pristine' means: Installing a ROM with no leftover from the previous ROM
Why should I "Go Pristine"?
Short answer: To prevent 95% of the problems experienced by others when installing a Custom ROM
Long answer:
When you install an App (.apk), the data saved by the App -- even the .apk itself! -- might be optimized/customized based on your previous ROM. This means that if you change your ROM, the data might cause problems due to the differences between your previous ROM and your latest ROM.
This is especially a problem if you 'change generations' (e.g., upgrading from GB to ICS or ICS to JB/JB+).
I *always* do Pristine ROM installations, and am glad to say that I managed to avoid about 95% of the problems experienced by other users of the ROM I used.
Additional Info: There's a hidden folder called .android_secure in the root directory of your SD Card. This folder is not visible when the card is mounted in your phone. It might contain settings that depends on what ROM you're using.
Are there Drawbacks of "Going Pristine"?
Unfortunately, there's no such thing as a free lunch. Here's a list of some potential drawbacks of Going Pristine. See if you can live with them; if you can't, then you shouldn't go pristine.
How do I "Go Pristine"?
I have been installing my ROMs with "Pristine" way. Yes, reinstalling everything *is* tedious, but as a benefit, the new ROM runs smoothly, and a lot of problems that others (who did not go the "Pristine" way) never happened on me.
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There you have it, a clear and complete description of "Going Pristine", complete with the steps and explanations.
Feel free to link to this thread, and as usual, if you find this thread helpful, leave a Thanks and/or rate this thread 5 stars.

What does "Going Pristine" means
Going 'Pristine' means: Installing a ROM with no leftover from the previous ROM
Why should I "Go Pristine"?
Short answer: To prevent 95% of the problems experienced by others when installing a Custom ROM
Long answer:
When you install an App (.apk), the data saved by the App -- even the .apk itself! -- might be optimized/customized based on your previous ROM. This means that if you change your ROM, the data might cause problems due to the differences between your previous ROM and your latest ROM.
This is especially a problem if you 'change generations' (e.g., upgrading from GB to ICS or ICS to JB/JB+).
I *always* do Pristine ROM installations, and am glad to say that I managed to avoid about 95% of the problems experienced by other users of the ROM I used.
Additional Info: There's a hidden folder called .android_secure in the root directory of your SD Card. This folder is not visible when the card is mounted in your phone. It might contain settings that depends on what ROM you're using.
Are there Drawbacks of "Going Pristine"?
Unfortunately, there's no such thing as a free lunch. Here's a list of some potential drawbacks of Going Pristine. See if you can live with them; if you can't, then you shouldn't go pristine.
- You will lose your savegames.
And thus, avid gamers will likely go insane due to having to repeat all the levels
However, please read the 2nd post of this thread for some interesting thoughts.
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- You will have to re-download all apps.
Which will be *very* time-consuming unless you have a fast HSDPA connection, or able to access a fast & free Wifi hotspot, or both.
Also, please read the 2nd post of this thread for some interesting thoughts.
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- You have to set some (relatively) significant time to do the process.
Trust me, copying 10 GB worth of stuff from/to the SD Card takes a loooong time, especially if there are a huge number of small files likeporn picscute kitten & puppies pics.
How do I "Go Pristine"?
- Make sure that you have ClockWorkMod installed
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- Make a backup of important data, such as SMS Log, Call Log, Contacts (if you don't sync to Google), etc.
No need to perform backup of apps, especially System apps!
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- Create a Nandroid backup of your current system, I suggest in .tar format instead of dup format.
This will be necessary if you need to go back to your previous ROM.
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- Turn off your phone, eject the SD Card
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- Backup (copy) the whole contents of the SD Card to a PC (Windows, Mac, Linux, no matter)
-- or --
Prepare a new SD Card
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- (Optional, but recommended, especially if you want to use Link2SD later on) Repartition your SD Card, even if it's previously partitioned.
Make 2 primary partitions; the 1st one as FAT32, the 2nd one as ext2
(You *don't* want ext3/4 on a flash memory. Trust me)
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- Format your SD Card accordingly. (I.e., 1st partition as FAT32, 2nd partition (if you made one) as ext2
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- Copy the following to the root directory of your SD Card:
- Your ROM installer updatezip
- (If needed/specified by the ROM) GApps updatezip
- The /clockworkmod directory from the previous SD Card contents (you did backup your SD Card, didn't you?)
- Insert your (partitioned, formatted, and copied-to) SD Card into your phone
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- Boot into Recovery
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- Wipe/format the following (find the proper entry in the CWM menu structure):
- /data
- /system
- /cache
- Dalvik Cache -- please note that this is *different* from the /cache of the previous line!
- Internal SD
- Battery Stats
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- Install your new ROM, following exactly the instructions by the ROM-cooker/dev
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- Now, this is VERY IMPORTANT: DO NOT EVER RESTORE ANY APP FROM YOUR PREVIOUS TITANIUM BACKUP SET!!!
ALWAYS DO FRESH INSTALLS FROM THE PLAY STORE!
You are allowed to restore some data, though: SMS Log, Call Log, and Contacts Book. That's it. Nothing else
However, please read the 2nd post of this thread for some interesting thoughts.
.
I have been installing my ROMs with "Pristine" way. Yes, reinstalling everything *is* tedious, but as a benefit, the new ROM runs smoothly, and a lot of problems that others (who did not go the "Pristine" way) never happened on me.
=====
There you have it, a clear and complete description of "Going Pristine", complete with the steps and explanations.
Feel free to link to this thread, and as usual, if you find this thread helpful, leave a Thanks and/or rate this thread 5 stars.
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