What Was Wayne Szalinski’s Old Job?

Wayne's job is never specifically mentioned in any of the canon, besides just being an inventor. WHich follows the Bungling Inventor:

A trope that started out as a subversion of the Gadgeteer Genius, but is now a trope in its own right, the Bungling Inventor is a scientist (often a Mad Scientist) whose inventions never seem to work properly. In fact, they're prone to truly spectacular cases of Phlebotinum Breakdown. The inventions might do something entirely different than what they were supposed to (like explode, or play "Yankee Doodle Dandy"), or they might seem to do their primary function but have some subtle flaw, or they might work a little too well (like a security robot that throws everyone out of a house, including the people it was designed to protect).

A second part of this inventor trope is the "down and out" in the fact that they likely quit their job to invent some kind of thing, that fails constantly and they consider going back to their old job.

One can assume that he used to work at a university, or some kind of institution, The one and only company mentioned ever is Sterling Labs, where Wayne works in the second film. Thusly one could conclude he may have worked at Sterling Labs.

But really it's not important where he worked, it was just a line to show that he probably has regrets trying to make a machine that doesn't work and being laughed out of the conference he was at.