Even though I use Adblock Plus and have specifically blocked certain tracking cookies (eg, alcmpm.com and pagefair.com — both of which boast of the ability to circumvent blocking by browsers such as Firefox as part of their online advertising), they regularly show up in my daily cookie list and have to be expunged just as regularly.

Query: Is there any way to definitively "kill" them?

I wonder if even though the cookies have been placed, Ghostery can prevent them from calling home?

(Understanding Little Snitch touches on this subject, but pretty obliquely.)

I used to use Ghostery but disabled it since it bogged down browser performance significantly.

Deep in the bowels of OS X is /private/etc/hosts, and if you'd care to jump through some hoops you can edit it to add URLs, and that will prevent any contact between anything on your Mac and them. (It was mentioned in my linked thread.)

I didn't think you'd be interested.

But you ought to take a look at Privacy Badger, which is discussed in this thread, and kinda reviewed (and linked to) here.

The updated Lifehacker article is excellent, but I'm pretty much following its recommendations already. Unfortunately, the two tracking cookies mentioned in my original query have worked out ways to get around evasive efforts.
I'm still trying to find a (reasonably simple — ie, no script writing or similar ploys about which I don't know anything and am not going to delude myself into attempting) way to "kill" the ability of these cookies to be placed. That said, I've checked when they show up (ie, which sites seem to be the ones which place them) and they seem to be more innocuous than evil. So, unless and until I can find what I want, I'm not going to install stuff on spec (cf the final paragraph of the article).