Two things to try that ought to clarify this issue for you...
1. Navigate to /Applications/System Preferences > Accounts > Login Items and hover your cursor over iTunesHelper; you'll see a Unix path.
Now move iTunes from /Apps to your desktop, and hovering will show you "Unknown".
Now move iTunes back, and hovering will show you the original Unix path.
2. Set EasyFind to "Search for: File Contents", and plug in NetShredX, USBOverdriveHelper, and WDDriverUtilityHelper, one at a time; each search should turn up /Users/xxx/Library/Preferences/loginwindow.plist...probably nothing else.
Those entries are your spurious login items that show "Unknown" in EtreCheck and when you hover your cursor over them in /Applications/System Preferences > Accounts > Login Items. Delete the login items from /Apps... and they'll disappear from your search results.
Hope this helps.
Last edited by artie505; 10/27/15 08:07 AM. Reason: Expand & clarify