I watched this last night (I only rented TF2, I swear!!) and it was honestly one of the funnier Trax I've seen. Although the final sequence in the desert still feels like a chore to watch even with their jokes, it just goes on and on and on, the phrase "Deep hurting!" comes to mind...but still the only way I'll ever watch that movie is with the Rifftrax commentary.
"...and Beavis and Butthead leave the theater feeling their intelligence insulted."