In the “anything goes” world of social media, it stands to reason that the language we find there isn’t exactly reserved for polite company.

And now we have some quantifiable data that confirms those suspicions. Reppler, a Palo Alto, CA-based social media monitoring service, recently scanned some 30,000 Facebook members’ walls … and what they found wassn’t exactly the language of choirboys.

Here are two interesting stats from what Reppler discovered:

 Nearly half of the Facebook walls contain some form of profanity.

 Four out of five users with profanity on their Facebook wall have at least one comment or post from a friend that contains profanity.

What’s the most common profane terms used? Not surprisingly, the “f-word” comes out on top. That’s followed by various derivations of the word the French know as merde. Runner-up among the top three is the “b-word.”

It’s important to note that people don’t have complete control over the language their Facebook friends use. But the prevalence of profanity on Facebook walls comes at a time when many employers are increasingly looking at the online presence of their prospective hires and noting the degree of professionalism – or lack thereof – that they see.

And there’s a related issue that’s becoming increasingly significant as well. With more companies and brands creating Facebook pages and other social networking sites, monitoring the discussion that takes place on them takes on even more importance.

It’s critical for brands not to offend even a small percentage of their customers. But with the general “race to the bottom” in what’s deemed acceptable language, there are real differences in what some people think is legitimate expression … and what others would consider to be gross indecency.

These differences are a factor of not only of age, but of acculturation.

Third-party tools from Reppler and others that automatically flag certain language or phrases can alleviate some of the problem, but there’s really no substitute for good, old-fashioned site monitoring. Which is why so many companies are finding the whole social media thing to be pretty labor-intensive, when done properly.