Road Runner a boy? Gosh, I always thought she was a girl! (S)he’s so clever and graceful…
I say it’s a wash between Wile E. Coyote and Acme. The Coyote has likely run up a huge bill by now with all the things Acme has sent to him, but yet he’s never paid for. Any settlement owed to Mr. Coyote from Acme would be cancelled out by the debt he has incurred over the years.
A couple other points:
If none of the products/devices/schemes have ever killed the Coyote or even debilitated him for very long, how can he expect them to be very effective on the Roadrunner?
If the Coyote is smart enough to build a fully-functional robotic likeness of himself from scraps he found in a junkyard, I’d say he should be working in some engineering firm instead of wasting his time chasing roadrunners out in the desert.
What does the Coyote use for sustenance while pursuing the Roadrunner? He has to be eating something to have all that energy to build traps or ways to make himself go faster.
Also, it seems that Acme products only fail when the Coyote uses them, but they work when the good guys use them (e.g. Bugs Bunny).
Yes, I know it’s “just a cartoon.” 
Another possibility is that Mr. Coyote is a beta tester for ACME and the products have been supplied free of charge. Or course in this case Mr. Coyote is likely bound by iron clad personal injury waivers. 