-- Issue-1
Install jre8 b20, then uninstall it, below registry item will be leaved behind it:
HKEY_LOCAL_MACHINE\Softward\MozillaPlugins\@java.com/DTPlugin,version=11.0.0

-- Issue-2
Install jre6u30, install jre8 b20, below registry node will be changed with less children nodes:
HKEY_LOCAL_MACHINE\SOFTWARE\JavaSoft\Java Web Start
After 6u30 installation, this node has about 7 or more children, but after install jre8 b20, it only has four children children nodes.
Note: jre8 b16 without this issue (but uninstall 8 b16 will remove almost all items under Java Web Start, jre8 b20 without the issue).

-- Issue-3
Install jre6u30, install jre8 b20, then uninstall jre8 b20. Auto Update version not recovered to old value for 6u30.
After install jre6u30 the Auto Update version is 2.0.6.1, after install jre8 b20 it changed to 2.1.5.3. After uninstall jre8 b20, the value still is 2.1.5.3
This issue also exists in jre8 b16.