The Blues set the gold standard for bad trades in the mid-80s - early 90s.
In the mid-80s they had a miserable owner who only survived getting murdered by Blues fans because he saved the team from moving. While he might've done that he was the cheapest SOB to ever live.
In '85, he traded Joe Mullen (who got 45g that year and in the prime of his career) to Calgary for the immortal Charlie Bourgeois, Gino Cavellini, and Eddie Beers after a contract squabble over just a few thousand dollars. Beers was supposed to be the prize, but blew out his knee and never played another game after '86. Mullen would lead Calgary to the Cup Finals in '86 (defeating the Blues in camp. finals of course) and have a great career.
And then of course in '88, most know the story. Dougie Gilmour (25 at the time) was accused of sexual harrassment by his 14yr old babysitter. He was under a ton of public scrutiny in St. Louis and Caron was forced to deal him and Mark Hunter to Calgary for Mike Bullard, Craig Coxe, and Tim Corkery. It was a miserable situation for all involved. Gilmour and Caron both cried after Dougie's departure. Gilmour loved St. Louis. The charges were later dropped. Such is life as Blues fan.
And then the topper was in 1990-91 (which is largely considered the worst in franchise history), when the Blues had a terrific team (Stevens, Hull, Oates, Brind 'Amour, Joseph) and were first overall in the conference at the trade deadline. Brian Sutter was enfatuated with guys like Garth Butcher and Caron didn't think the team was tough enough. So they unbelievably deal off Geoff Courtnall, Cliff Ronning, Sergio Momesso and Robert Dirk to Vancouver for Butcher and Dan Quinn.
Basically they traded 2/3rd of their second line and most of their secondary scoring which just allowed teams to double team Hull cause there was no other threat offensively. They had no depth and bowed out to the North Stars in the second round. Stevens would be awarded to NJ in the offseason. And that was that.