Yes, the Scunthorpe problem: http://en.wikipedia.org/wiki/Scunthorpe_problem

After college I worked as a network administrator for a doctors office that dealt with pain medications. We constantly had problems with work mail going to the spam folder when it actually concerned drugs like Vicodin.

The salient point here is the email have to already be in the spam box. If Gmail already thinks it's spam AND it contains any of the keywords, then it gets trashed.

That being said, you still have a point.