It probably takes less than a second to restore them because those cookies are opt-out cookies that are created by the TACO extension. Such cookies can only be removed if you uninstall that extension.

Targeted Advertising Cookie Opt-Out (TACO): https://addons.mozilla.org/firefox/addon/11073

TACO with Abine prevents over 100 different online advertising networks (including Google, Microsoft and Yahoo) from displaying highly targeted advertisements using the detailed information on your web surfing habits. TACO disables most behavioral advertising by setting 100+ permanent, generic, non personally identifiable "opt-out" cookies directly into the browser.

Unlike other opt-out solutions, this tool will make the opt out cookies completely persistent. That is, clearing the browser's cookies will delete all other installed cookies, except these.

Thanks, I hadn't thought of that. Some of the cookies had "Opt Out" descriptions, but some didn't. I appreciate your help.

You're welcome.