Excessively vain of humans to think that not only are we interesting enough to visit, we are also smart enough to catch them when they don't want to
be seen.
If a UFO ever turns up it will be some sort of Warship/Resource collector and anal probes will be the least of our worries.
Maybe what we see as lights on the craft is actually our eyes interpretation of energy fields.
Have a look at a picture of the sun, now look at the sun through different wavelengths...
Who knows
We can only see a small spectrum of light & our brain is always "filling in" gaps to what we actually perceive as reality.