Well that was a change in appearance. Like a vampiric version of Neo from the Matrix, Sam observed. Probably, he should have cared. At home, he would have been freaking out. But he'd learned a lot since then. About life and where his was destined to go and he'd had a lot of time to reflect on what was different between 'good' and 'evil.' The line wasn't as thick as he'd initially thought, really. Dean would probably run him over a million times with the Impala for even entertaining that thought, but it was this place. It was doing weird things to his head, he decided.
He didn't get why people felt betrayed or angry at this guy for lying. It was a huge deal. Sam wouldn't want to be honest if he were an 'epic betrayer of organized relig-' he almost laughed at that thought. Because yeah, he totally got why the guy hadn't spoken up. Same reason Sam hadn't spoken up about opening Lucifer's cage and siccing him on his own universe, maybe?
They weren't really different, Sam decided. Maybe it was an entirely different level, but they had a bit in common. By giving in to destiny, they isolated themselves and betrayed people they loved...and in Sam's own world, it seemed that he had to live with it forever, too. Trapped with Lucifer inside his own head in that damn cage for the rest of eternity. Or until someone else screwed up and let him out. In which case, he hoped his control wasn't temporary, or else the world was in for some unpleasantness. The offer of 'penny for your thoughts' made Sam shrug. There was way, way too much to narrow down into one particular sentence.
"Just now? I was thinking about the fact that we're really not that different. Well we are, but we're not at the same time..." he said simply, inwardly cursing the god damn truth serum, but he really didn't care. He hated lying. Why he felt compelled to be honest to a stranger was beyond him, but he was just tired of not being upfront.