I see this all the time. People think they are fully wiping when a developer asks for it. I believe that some people still don't understand what a full wipe is because there is no such single option in ClockWorkMod Recovery. Most likely the reason for that is because Koush didn't want too many posts about "I'm stuck on Google logo" or "my phone won't boot". So here is a test you can do yourself: Backup your ROM of course, and then do a full wipe. Then don't install anything and just reboot. If you end up pass the Google logo and onto the boot loop screen, then what you think is a full wipe is incorrect. If you are stuck on the Google logo and nothing is happening however, then congratulations... you know what you're doing
For the rest of you, here are proper steps to fully wipe without leaving any trace of ROM on your phone:
- wipe data/factory reset
- format /system
- format /boot
Now most people think that the first option is enough. That may often be the case but because the developer can drastically change the contents of the /system folder, things can get messed up if you don't format it. And guess what, that first option will not do it. Wipe data/factory reset only wipes the /data folder which contains your personal settings and all the apps you installed. The ROM is then left blank as if you just flashed it and you can start over. FYI, the format of boot partition simply wipes the boot animation and you can restore it using the advance option in recovery from ROM to another.
I've seen some zip files which do this automatically so that's fine but at least you know what needs to be done to fully wipe.
There you go. I hope this clears some things. Now lets flash some ROMs!