I think what OP means is using a regular browser but having his computer set to "Private Browsing" or "Incognito" mode, in which his computer doesn't save cookies or records from the sites he's visited.
Both your Blacklist and your My Tags lists are saved in the cookies on your computer, not on the website itself, so with no cookies retained in Private Browsing mode they both get cleared each time you log out.
The fix is to keep a text file of your Blacklist that you can quickly copy and paste each time you log in. Either the "Stickies" or "Sticky Notes" programs should work well for that.