During "Chuck vs. The Fat Lady", the most recent episode aired of 'Chuck', his ex-girlfriend revealed that her boss had been so paranoid about his computer being hacked that he used a random piece of Vogon poetry as his computer password.
As fans of Douglas Adams' "The Hitch-Hiker's Guide To The Galaxy" know, Vogon poetry is the third worst poetry in the TV universe. "HHG2TG" exists on just about every level of the multi-versal plane, beginning with the sublime radio series, through books, a TV series, interactive games, and the very disappointing movie.
But in all of the variations, one of the constants is that Vogon poetry is perfect as a torture device. (I'll bet Dick Cheney reads a verse or two every day, just to get his day off to a good start.) The example used in the TV series, which is the only version we should be concerned with in Toobworld, was used to torture Arthur Dent and Ford Prefect, and can be seen here to the right.
Based on the six-part TV series, the human race was not aware of the Vogons until the day they showed up around 1980 with their constructor fleet, which hovered in the air in the same way that bricks don't. (I think that has always been my favorite descriptive phrase in all of the series.) The Vogons arrived to vaporize the Earth (Earth Prime-Time to be specific) in order to make way for a hyperspace bypass.
Which they did.
And yet, as evidenced by 'Chuck', Toobworld is still around.
The history of Earth Prime-Time has been remade several times over since its destruction in 1980. Although it would happen again in 'Primeval', it was because of Ford and Arthur's interference back in the caveman days once they journeyed back in Time which resulted in the Earth's continued existence beyond its original destruction in 1980. I don't know exactly what they may have done to have caused this, but it led to there being a change in plans for that hyperspace bypass; the Vogons didn't come to destroy Toobworld in the new timeline.
But in this new timeline, Earth was still made aware of the existence of Vogons, and this time for more than five minutes. And although no mention has been made of it in other TV shows that share the same dimension as 'The Hitch-Hiker's Guide To The Galaxy' and 'Chuck', apparently their existence is known to the general public, based on Jill's revelation about her boss' Vogon password.
It's possible that in her field of expertise (and as we now know, because she was an agent of Fulcrum), Jill would have granted access to the information that the Vogons exist. Major John Casey and Agent Sarah Walker might have had the necessary security access to see such an "For Your Eyes Only" type of file. But even though he was the "Asset", the walking, talking embodiment of the Intersect, there's no way the government would have allowed Chuck to know about the existence of such alien life - unless it was already common knowledge among the people of Earth.
For whatever reason they came to Toobworld, the Vogons - bureaucrats that they are - could possibly be working for the US government in some mind-numbingly mundane capacity.
What we need is a live-action version of "Men In Black" to use as an entry point for their presence on Earth Prime-Time. And because the Men in Black seem to exist in 'The X-Files' episode "Jose Chung's From Outer Space", we're good!