Walt fabricates the poorest lies I've ever heard. He knows people won't truly believe them, & he knows they'll know that about him. "He's telling lies he'll know I won't believe". He does it anyway, because by doing so, he looks sad, desperate, & weak, like a victim with no alternative but to conjure sad bullshit. It's his whole gambit, playing the schnuck. Walt is Keyser Soze. He'll stare you right in the face & you'll think how could anyone be so pitiful?
I thought some of this previous lies were rather good, but this one was just painfully
bad and transparent-- which may have been intentional by the writers, to show that he's not as much on his game as he used to be.
Although I couldn't help but wonder why Walt went through so much trouble to come up with a ridiculous story anyway
. It felt more like something he'd do in Season One, when he was much more concerned with hiding the truth from Skyler.
With Jesse and Hank bearing down on him, and the noose slowly tightening around his neck, it's a bit hard to believe he'd care so much about a gasoline-soaked carpet. Especially when, as we saw later, they've got more
than enough money to stay elsewhere.