It’s an old adage here at the Daily: Rats belong in the sewer, blenders belong in the kitchen, and never the two shall meet.

That life lesson was apparently lost on the powers-that-be at NBC, which crossed the vermin-kitchen appliance line in November when it forced contestants on “Fear Factor” to prepare and choke down a serving of Puree Master Splinter for a shot at $50,000.

The stunt was apparently too much for Austin Aitken, a Cleveland paralegal who sued the network for $2.5 million last week, saying the segment made him physically sick.

Aitken’s motives for the lawsuit are suspect — he reportedly told Reuters news service that he couldn’t discuss the case unless it was a “paid-interview situation” — but his point is well taken.

Entertainment media today, with reality TV leading the charge, seem to be lacking their most basic tenets: entertainment and any semblance of reality. Rat blending on “Fear Factor” is not an isolated case; in fact, it’s becoming the disgusting, debasing norm.

• On a recent episode of MTV’s “Real World/Road Rules Challenge,” teams raced to lick live insects from the body of a teammate, chew them up and spit the remains into translucent jugs.

• On Fox’s “Who’s Your Daddy” special last week, an adopted woman attempted to win $100,000 by picking her biological father out of a room of men trying to fool her to win their own 100 grand.

• On Fox’s “The Swan” last fall, women were subjected to numerous cosmetic surgeries to make them “beautiful,” then judged individually and rejected one-by-one for not being beautiful enough, until only one remained. This last contestant standing won $300,000 in money and prizes and, apparently, divorce papers from her husband. True to the “reality” ethos, the show’s cameras were there for all the surgeries — and when the woman was served with the divorce documents.

It’s not hard to find the common theme among these shows — duh, it’s the dollar sign and all those zeroes — and that’s perhaps the most disturbing thing about their existence. Not only will Americans do anything for money, be it violating their digestive systems, physical appearance or interpersonal relationships, but they will also watch as other people do these stupefying things.

Aitken’s lawsuit against NBC sounds like little more than an attention-and-money grab by a middle class stiff, a motive not unlike those of a reality TV contestant. But at least his raises an awareness of the direction our culture is headed instead of helping to drag it down further.