Spitting in opponent's lane

I recently heard that a woman swimmer, unnamed, on the elite level, has been known to spit in her opponent's lane before a sprint race. Is this just ill-mannered pscyhing or something more sinister? I read on one of Gary Hall Jr.'s race club blogs that this might be a technique for getting a competitor to test positive for steroids or other drugs. This has a somewhat Urban Legend quality to it that causes my spider sense to tingle. Nevertheless, I am wondering if the more knowledgable folks on the forum might have an explanation for the strategic use of spittle.