It was the first time in his life Isaac didn’t want to go to Vegas.

He is an avid Craps player. He goes to Vegas several times a year. And he was set to spend two days with a large group of his oldest friends. But he was looking for any excuse to get out of the trip.

For the past couple of years Isaac has been following his childhood friend Marvin on Facebook. And over that period, Marvin has shared a series of political links and comments that are diametrically opposed to Isaac’s core values. During the weeks leading up to the trip, Isaac was convinced that these political differences would be a thorn in the side of any experience.

But a funny thing happened when he got to Las Vegas. For the first time in years, Isaac saw his old friend Marvin in person. Within ten seconds of greeting each other, Isaac was reminded that in addition to a shared history and group of friends, he and Marvin have almost everything else – from guitar playing to favorite books – in common. They talked for hours that first night in Vegas and the bonding session extended right through Sunday afternoon.

After the trip, Isaac called me to recount the many highlights of the weekend, from winning a few grand at the tables to watching baseball on the big screen in our poolside cabana. “You know what my favorite part of the trip was?” he asked. “Hanging out with Marvin. I forgot how much I love that guy.”

What happens in Facebook should stay in Facebook.

Online, Isaac had been encountering a few random droplets of digital paint. When he got to Vegas, those random splatterings were replaced by an entire canvas of a relationship both he and Marvin had been painting for a lifetime.

Even habitual oversharers only share a subsection of themselves on social networks. That subsection could be entirely different from what they share offline. And even if it isn’t, the stream of updates, links and shared content can only represent a tiny part of anyone’s total personality.

Is it worth it for Marvin to consider which aspect of his personality he’s sharing on Facebook and whether he wants to lead with politics? Sure. But again, no one can share it all.

And it’s not just about politics or other topics we often try to avoid in face-to-face conversations. Aren’t there some people about whom your opinion has changed since you started communicating online? There are several old friends who I now like a lot less because they sort of suck at Facebook.

So I hide them from my life when I should probably just be hiding them from my stream.

From my mom, I inherited the gift of summing someone up with a glance. I just get a vibe and it’s almost always on the mark. I once correctly assessed one of my sister’s boyfriends as a complete chump from over one hundred yards away. But I don’t often get a gut reaction online and when I do, it’s often wrong.

I’m not arguing that there is no overlap between your online and offline personalities. But someone who only experiences the virtual you is not getting anywhere close to the full story.

Most people know this is true when it comes to celebrities, public figures and folks you only encounter via online communities. But they still make judgments when that’s the only content they have to go on. And Facebook and Twitter are becoming such an integrated part of our social lives that the content you find there can alter or even completely distort the opinion you have of friends you’ve known your whole life.

For Isaac, online and abridged Marvin had completely replaced real life Marvin.

Sure, that all changed once they spent some in-person time together. But these human to human connections seem to be losing some of their currency in an era where so much of our social networking has moved online. It’s getting harder to distinguish the online parts from the real life whole.

That’s the power of the internet. It managed to turn Vegas into real life.

This post originally appeared in Tweetage Wasteland which has been merged with NextDraft.