Semi-OT: Detection of ETs

[pmulcahy11b]

I'm watching a show on the History Channel about possible visitations by ETs to the Earth. Supposedly, there have been several radar returns and even tracking of these UFOs.

My question is: How? We have stealth technology that can reduce the radar return of an aircraft the size of a B-2 Spirit to that of a bumblebee, as well as greatly reduce the IR signature. It seems that a civilization capable of crossing the stars would have stealth capabilities beyond out imagination, maybe up to outright invisibility to the entire electromagnetic spectrum. I can't imagine that any technology on earth could detect them if they didn't want to be seen.

And that's the only thing I could think of for any possible detections of UFOs -- they don't care if they're seen, because they consider us to be no threat since our weapons are too primitive to bother them.