Mrs. Blogfoot remembered the ads though, so I know I'm not crazy. This also confirmed that I married the right woman. I mean, come on...she remembers 30 year-old commercials with robots wearing jeans and can quote "Wrath of Khan" at will. Truly a rare cut of stone, as they say.
Anyhoo, when queried about this, a friend mentioned a brand of jeans from the 70's that I had forgotten about: "Toughskins." Yes, Toughskins, the low-cost, in-house brand foisted upon the children of the non-rich by the fiends at Sears. Toughskins debuted as a new blend of materials, including Dacron Type 59 polyester, DuPont 420 nylon, and cotton. They touted the line of Toughskins children's pants as "The toughest of Sears tough jeans...lab tests prove it!"
"Lab tests", hey? Is it such a stretch to think that a company that talked of "lab tests" would also belch forth a jean-wearing robot as a pitchman? No, it is not a stretch at all. But sadly, all I could find a record of was another campaign they did in which they constructed a trampoline out of the Toughskin material. I've pasted a blurry clip of this ad below, and you can read the truncated history of the toughskins brand here.

Toughskins also featured re-inforced knees as a selling point, which would dovetail nicely into my memory of the robot doing knee bends in the jeans to illustrate their resiliency. And the fact that they were dirt-cheap would dovetail nicely with the memory of my brother and I being forced to wear them. Although once they trotted out the robot, I'm sure I was begging for them.
Why is there no record of this? WTF? Is no one with me? What's the matter with all of you? Doesn't the thought of a jean-wearing robot interest you? I think it does! Hop to it!