Dean probably would have noticed that there was something a bit off with the poker game that he'd practically gate-crashed if he hadn't been drunk at the time. What he did notice was that it had taken his last five-hundred dollars to bribe his way to the table where there were piles of chips and money.
At some point near dawn, Dean and a short dark haired, dark eyed man in black who spoke with an English accent were the only two at the table. In the middle of the table was a pile of cash and a large number of chips.
"Tell you what." the man in black said as he pushed the last of the cash forward. "If you throw in your soul, I'll throw in my dog Max here."
The man in black patted something invisible that was somewhere at his chest level before tossing a set of pet tags on the table.
"Yeah, sure, whatever." a completely smashed Dean who was eying all of the money in front of him said.
"That didn't go as planned." Crowley said ten minutes later as Dean Winchester walked off into the sunrise with about fifty grand in cash, twenty-seven contracts, and the hellhound he'd fondly nicknamed Stupid on a leash.