By this point, Jack couldn't even tell him which bar it is, mostly because he doesn't care. It's got somewhere to sit and it's got alcohol, and that's all he needs.
He looks round rather blearily at the sound of Spike's voice. He's not really that drunk; it's more general lethary, along with a specific feeling of really not wanting to have to deal with Spike right now - whilst knowing with absolute certainty that it was only going to be a matter of time that he had to.