Why is this the least popular film he made with Carl Reiner?
It is the responsibility of the working film critic to not only offer opinion and context for the newest releases, but also to constantly champion and curate the films that matter, especially if they were misunderstood or poorly released or somehow handled badly the first time around.
Critics should take it upon themselves to rehabilitate the under-loved, to defend the wrongly-maligned, and rehab the films that need it; it is the only way film as a whole can be healthy.
"When I saw how slimy the human brain was, I knew that's what I wanted to do for the rest of my life."
Genre parody is a very tricky business.
In general, laughter and scares seem like the perfect combination, and when people get it right, it can make for a very appealing rollercoaster ride. One of the things that I love about the collaborations between Carl Reiner and Steve Martin is that they seemed determined not to repeat themselves. In some ways, they strike me as not unlike Gene Wilder and Mel Brooks, guys with fairly different comic sensibilities who came together and created a group of movies that are unlike anything either of them did on their own. I can't imagine "Blazing Saddles" or "The Producers" without Wilder, and I can't imagine he would have had the same luck with any other director that he did with Brooks on "Young Frankenstein." Martin and Reiner's "The Jerk" seemed to be drawn largely from the persona Martin had already created, but "Dead Men Don't Wear Plaid" was a great, strange movie experiment that Reiner had to nail in terms of every single visual detail if the joke was going to work at all.