I have spoken to beings which claimed to be aliens, but that was with the use of advanced psychological fine-tuning techniques. It's more likely that they originated in my own brain than extraterrestrialy.
I'm currently working on techniques for alien recognition, and I suppose that my success depends on how advanced their deception technology is and how willing or unwilling they are to be found.
An unwilling alien with very futurist humanoid-form technology is likely to be indistinguishable from a normal human. I do think that it's more likely that I'll find aliens in the higher levels of business and government, and in fringe occult groups, though. Why would an alien come to earth just to be a housewife? They're probably pushing their alien agenda, and the aforementioned groups seem like the most likely place that they would do so.
If an alien has very different reasoning to a magician such as myself, though, there may be no way of telling where it will appear.